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1. 10 11 12 HI HI LO LO SRC SEN SRC SEN A4 B4 BANK 4 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 4 6 Figure 4 3 Model 7702 screw terminal channel designations CH4 CH6 CH8 CH10 CH12 CH14 CH16 HL HL HL HL HL HL HL CH18 CH5 CH7 CH9 CH11 CH13 CH15 CH17 HL CH3 HL HL HL HL HL HL HL HL 19 HL CH2 H L CH20 H L CH1 HL f 2 2 AD ziziziziziziz AAA al estan zziz ev i 4 Oo N sj 121 af LLL LL ILLI ll Ss SSSS55555 SSS LILILIL zzz IEEE SEREEEEE V saps a FRR HL CH21 HL H L CH40 CH22 Hd i HL IHL HL H L CH26 H L HL CH39 CH28 2 CH34 cre a CH23 HL HL HL HL HL HL HL CH35 CH37 CH25 CH27 CH29 CH31 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 279
2. Ch 13 Source HI Chi chia Bank 1 Sense J101 ource 0 0 LO Ch 2 es Sense 10 c Ch 3 1 Ch 16 B1 Model 2790 Backplane Source Ch 4 1 Bank 2 102 iB Source E ERE 19 Source Enable 4 Sense 5V 1106 EE 2 um d B20 o Guard Guard 5 Source ource ax T HT O Source jos Sense O Source LO Sense LO NM Ch B be HI A30 o f c o VOUT J108 B3 Ch 9 1 o I VLO Vsrc HI Source Ch 10 Vsrc LO Bank 4 Sense 0 07 il Isrc 1107 J104 Isrc LO Source L Ch 11 HL Guard Sense o o o O Guard EC ai Ill 200 7751 3 20 7753 Vsource vd xd Ch 28 urrent Voltage 7751 7753 50 500 Amplifier Only 7751 7753 Only 1 SSS SS Ch 24 Isource Ch 27 lo soma Cable Discharge Ch 21 0751 7753 Only V So rem 5 1 22 Open I source Select Ch 22 Close V source Select Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 4 Model 2790 SourceMeter Switch System User s Manual l source channels 21 22 24 and 27 The programmable I source 0 to 50mA is used as the test current to measure low resis tance inflator bridgewires and shunt bars
3. 2 21 Memory pattern command options 2 22 Memory pattern scanning 2 22 Memory pattern log setis ette hcec 2 23 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 3 Keithley 7702 Switching Module Safety precautions s c ce aeter ea 3 2 Card conBguration iecore p nene RE 3 3 CONMECH teet ee erede 3 5 Connection lop 129 RD IEEE 3 7 Opening and closing 7702 channels sess 3 9 Channel assignments essere 3 9 Front patiel Operation nce tete ttn itt 3 10 Remote programming 2 3 11 Viewing closed channels 3 12 Using 7751 7753 V source with 7702 module 3 13 4 Switching Module Wiring and Installation Connections and Witing teens ettet retenue 4 2 Screw terminals o 4 2 Cabling requirements 4 3 Wiring ptocedure edge ime reet ripe 4 4 ZippertubingG shield cse ces 4 8 urinae 4 9 Switching module installation eee 4 10 Module slot considerations eee 4 10 Power supply restrictions with the 7753 module 4 10 Installation procedure eene 4 10 5 Inflator Testing Introduction 5 2 56 29 5 2
4. Display MULT option CLOSE MULT and press ENTER CLOSE MULT XXX Remote programming The commands to control 7751 7752 and 7753 channels are listed in Table 2 3 Specify channel number XXX and press ENTER Table 2 3 Commands to control 7751 7752 7753 module channels Commands Description ROUTe MULTiple CLOSe lt clist gt ROUTe MULTiple OPEN lt clist gt Specify one or more channels to close Open channels specified in list Unlisted channels not affected ROUTe OPEN ALL ROUTe MULTiple CLOSe ROUTe MULTiple CLOSe STATe lt clist gt Open all channels Returns a lt clist gt of all closed channels Query closed channels in specified list 0 open closed ROUT OPEN ALL will open all channels except channel 20 if interlock is open Examples ROUT OPEN ALL Open all channels ROUT MULT CLOS 101 114 118 Close channels for slot 1 ROUT MULT CLOS Return list of closed channels Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 15 Viewing closed channels Closed channels can be viewed from the VIEW item of the CARD menu The menu struc ture is accessed by pressing and releasing SHIFT and then pressing CARD As shown in Figure 2 5 the closed channels will scroll across the display The four dots identify the end of the channel string Use the E
5. The I source is designated as channel 27 Opening channel 22 selects the I source Closing channel 21 connects the I source e Closing channel 24 connects the dry circuit clamp for the shunt bar test 20mV ImA limit NOTE Ohms specification calculations in Appendix A explains how to determine the accuracy specification for source levels not specified in the 7751 7752 7753 SourcelSwitch Module Specifications sheet V source and I V amplifier 7751 7753 only channels 21 22 23 28 The programmable voltage source 50 to 500V and I V amplifier are used to measure high resistance insulation resistance of an inflator The V source is designated as channel 28 Closing channel 22 selects the V source Closing channel 21 connects the V source Closing channel 23 connects the I V amplifier WARNING not connect V source Hi to earth ground The 7751 7752 7753 mod ule uses a floating ground This floating ground is not connected to safety earth ground Not only will it create a shock hazard by floating up to 500V it will also effectively connect a 1nF capacitor across the V source providing energy storage that could ignite an airbag under fault conditions NOTE Ohms specification calculations in Appendix A explains how to determine the accuracy specification for source levels not specified in the 7751 7752 7753 SourcelSwitch Module Specifications sheet Cable discharge 7751 7753 only channel 20
6. VsrcHI 1 oe Vsrc LO 107 B3 Isrc HI Source ooo Isrc LO HI Ch 10 1 10K Bank 4 Sense o o Guard J104 Source oto Guard 1 LO Ch 11 Sense c 4 9 6 Ch 12 Bto 9 200 7751 20 7753 lw Current Voltage Amplifier Vsource 50 500V 7751 7753 Only Ch 28 a 7751 7753 Only pM _ 4 Isource Ch 27 Ch 22 Open Isource Select Ch 22 Close Vsource Select Cable Discharge 7751 7753 Only HW 11 04 03 Rev D Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications 2790 MAINFRAME FUNCTION SPECIFICATION MAINFRAME FUNCTION ACCURACY SPECIFICATIONS ARE FOR 1 YEAR 23 5 DC MEASUREMENT SPECIFICATIONS CONDITIONS MED 1 PLC or 10 PLC ACCURACY ppm of reading ppm of range or MED 1 PLC with Digital Filter of 10 ppm parts per million e g 10 0 001 Input Resistance or Test Current 5 Open Ckt 24 Hour 90 Day 1 Year Temperature Coefficient Function Range Resolution Burden Voltage Voltage 23 1 239 45 23 C 5 09 189 amp 28 40 C Voltage 100 0000 mV 0 1 uV gt 10 GQ 15 30 25 70 30 70 1 5 1 000000 1 0 gt 10 GQ 15 6 25 7 30 7 1 10 00000 10 pV gt 10 GQ 10 4 20 5 30 5 1 0 100 0000 100 10 1 15 6 45 9 55 9 5 1 1000
7. A cable discharge circuit is used to dissipate charge build up on the inputs to prevent acci dental ignition of the inflator For details see Cable discharge circuit Closing channel 20 discharges voltage on the input channels Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 5 Source readback channels 13 and 25 The actual output of the selected source can be verified by using source readback which routes the selected source back to the DMM of the 2790 for measurement I source and V source readback are explained in Section 5 Opening channel 22 and closing channels 21 25 and 18 connects the I source sense resistor to the DMM of the Model 2790 Closing channels 22 21 13 and 18 connects the V source to the DMM of the Model 2790 Interlock 106 7751 7752 7753 module has an interlock to disconnect its I source and V source from the rest of the switch matrix In order to use the module sources interlock must be enabled The interlock switch of a test station is connected to the J106 terminals of the module When the interlock switch is open 1 safety shield open the sources cannot be connected to the switch matrix Details on interlock are provided in Section 5 NOTE Interlock switch does not affect the output of J107 Voltage can still be present at those terminals even if the interlo
8. s Manual Keithley 7751 7752 and 7753 modules The 7751 7752 and 7753 modules can also be used with the Q2 and Q4 functions of the Model 2790 However since these modules do not support system channel operation the user must close all appropriate channels using multiple channel operation to make the con nection to the DUT Details on multiple channel operation are provided in Section 2 Figure 6 5 shows the simplified test circuit for using the 04 function of the Model 2790 with the 7751 7752 7753 module to measure the resistance of a DUT The DUT 15 con nected to channels 10 and 11 Bank 4 of the 7751 7752 7753 To connect the DUT to the DMM of the Model 2790 channels 10 11 13 18 and 19 must be closed Note that the voltage across the DUT is not sensed through the fuse resistance see Fuse resistance considerations page 6 2 so that measurement accuracy is not affected by fuses Figure 6 5 Using Model 2790 4 wire ohms with 7751 7752 7753 module low ohms measurements Sree 1 i 1 1 Fuse Keithley 7751 7752 7753 1 Resistance Input HI 18 13 10 T Ch 10 Sense 19 DUT 19 Sense LO Input LO 6 Channel closed by user multiple channel operation Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 6 9 Figure 6 6 shows the simpli
9. teinte e dr ero trt eec 6 2 Low ohms measurements 400 6 2 Fuse resistance considerations 2 6 2 High ohms measurements 6 3 4 wire ohimns 4 iet bende bees nicis cette 6 3 Offset compensated ohms 2 6 5 Keithley 7702 2 Donde 6 6 Keithley 7751 7752 7753 modules 6 8 A Specifications Models 2790 7751 7752 7753 and 7702 1 Ohms specification calculations 7751 7752 1753 A 8 VISTITES2ITIS3 ESOUECO s dert tret A 8 7791 7793 Oed 9 Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com List of Illustrations 1 Test System Overview Figure 1 1 System CONMECHONG wesc ahi aides satiated 1 5 Figure 1 2 shunt DAE TESTING e P init aere dna 1 7 Figure 1 3 Bridgewire epo ERE Ee EO 1 8 Figure 1 4 HIPOT testing 7751 7753 uiro ee eee eris 1 9 2 Keithley 7751 7752 and 7753 Switching Modules Figure 2 1 Simplified schematic of Keithley 7751 7752 and 7753 switching modules ne eet ette etras 2 3 Figure 2 2 Setting I source and V source output levels 2 7 Figure 2 3 Enabling ohms math function 2 11 Figure 2 4 Opening and closing channels esses 2 14 Figure 2 5 Vi
10. TeSt procedures sno pre dp ste tpe perde scene 5 2 Closed channels for test circuits eese 5 3 sies enit eerie et 5 3 RS 232 interface PLC or 5 4 GPIB PC Only caretes terea ttt UE Ports 5 4 Test signal connectiofis eio tereti ehe eoo ERE 5 5 liri ge E a ea EE e OEE E EE 5 9 Shunt bar test rond e e 5 10 5 11 Test procedure zu a getan RI 5 12 I soutce reddback mac decrevit 5 12 Bridgewire tests zn enn ordeo ae ea ig 5 14 CITCU E he 5 14 ORE 5 15 I soutce readback centre ree 5 16 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Insulation resistance tests 7751 7753 only 5 17 Contact CHECKS ode aee iiec on beers 5 18 Veso ice 5 22 Cable discharge nou rtt regie 5 23 e 5 24 Test procedure eee 5 26 I sourcedeadback ederet 5 28 Memory patterns test met reden ERI Eig epa 5 30 Mic c X 5 30 Test procedure 2 0 nitet temere d 5 31 6 Model 2790 DMM Ohms Functions Ititro ductlOn
11. Y IV Amplifier 1 1 i i 2790 VsOURCE 1 i 500 1 i 7751 7753 DMM 4j quinos i boa MENORES OREL i i De 2 1 RF 200kQ 7751 VMEAS Rr 20kQ 7753 22 500V kg VMEAS Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 1 10 Model 2790 SourceMeter Switch System User s Manual With the high ohms math function Sx Vohms selected the reading can be read directly from the display of the Model 2790 Before measuring Ryypor there are a couple of preliminary verification tests that should be performed first e Contact checks To properly perform the HIPOT test contact must be made to the air bag inflator housing If good contact is not established the measured high resistance will not represent the isolation resistance Contact is checked by per forming continuity checks through the V source test leads and the connection points The resistance reading for a contact should be less than 20 ohms depending on cabling V source readback Before performing the HIPOT test the output voltage of the V source should be verified The V source readback circuit allows you to directly measure the output voltage using the DMM of the Model 2790 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 Keithley 7751 7752 and 7753
12. 000 1 10 0 1 20 6 3549 50 9 5 1 Resistance 100 0000 Q 100 pQ 1 6 6 V 20 20 80 20 100 20 8 1 1 000000 1mQ 1 mA 6 6 V 20 6 80 6 100 6 8 1 C 10 00000 10mQ 100 pA 6 6 V 20 6 80 6 100 6 8 100 0000 100 mQ 10 pA 12 8 V 20 6 80 10 100 10 8 1 000000 MQ 10 Q 10 pA 12 8 V 20 6 80 10 100 10 8 1 C 10 00000 10 Q Note 7 70 150 6 200 10 400 10 70 1 C 100 0000 100 Note 7 70 800 30 3000 30 3000 30 385 1 C Continuity ZW 1 000 100 mQ 1 6 6 V 40 100 100 100 100 100 8 Current 20 00000 mA 10 nA 02 V 60 30 300 80 500 80 50 5 C 100 0000 mA 100 nA lt 0 05 V 100 300 300 800 500 800 50 50 C 1 000000 1 0 pA 03 v 200 30 500 80 800 80 50 5 C 3 000000 10 pA Lo v 1000 15 1200 40 1200 40 50 5 Channel Ratio Ratio Accuracy Accuracy of selected Channel Range Accuracy of Paired Channel Range Channel Average Average Accuracy Accuracy of selected Channel Range Accuracy of Paired Channel Range DC Operating Characteristics Temperature 60Hz 50Hz Operation Displayed in C F or K Exclusive of probe errors Function Digits Readings s PLCs Accuracy Temperature Coefficient TT Range Resolution 1 Year 23 C 5 0 189 amp 28 40 C DCV DCI 6 5 5 4 10 p 15 4 Wire RTD SemS Cr 6 5 W 1000 platinum PT100 D100 F100 PT385 PT3916 or user type Offset
13. 101 114 118 Set channels 1 14 and 18 for memory location 1 ROUT MEM DEL 1 0 Set delay to 0 ROUT MEM READ STAT 1 ON Enable reading SENS FUNC RES M1 Select 2 wire ohms SENS RES RANG 100 M1 Select 100Q range SENS RES NPLC 1 M1 Select 1 PLC Set up memory location 2 ROUT MEM CHAN 2 104 114 118 Set channels 4 14 and 18 for memory location 2 ROUT MEM DEL 2 0 Set delay to 0 ROUT MEM READ STAT 2 ON Enable reading SENS FUNC RES M2 Select 2 wire ohms SENS RES RANG 100 M2 Select 100Q range SENS RES NPLC 1 M2 Select 1 PLC Set up memory location 3 ROUT MEM CHAN 3 108 115 118 Set channels 8 15 and 18 for memory location 3 ROUT MEM DEL 3 0 Set delay to 0 ROUT MEM READ STAT 3 0 Enable reading SENS FUNC RES M3 Select 2 wire ohms SENS RES RANG 100 M3 Select 100Q range SENS RES NPLC 1 M3 Select 1 PLC FORM ELEM READ Send readings only from buffer Recall memory locations trigger request readings ROUT MEM REC 1 Recall memory pattern 1 READ Trigger and request reading ROUT MEM REC 2 Recall memory pattern 2 READ Trigger and request reading ROUT MEM REC 3 Recall memory pattern 3 READ Trigger and request reading Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 34 Model 2790 SourceMeter Switch System User s Manual Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02
14. 2790 in the one shot trigger mode For front panel operation FACT defaults places the 27790 in the continuous trigger mode This step sets the V source to output 500V which is a typical voltage for this test Note that this menu is also used to set the I source output Simply skip over the I source setting This step selects the high resistance calculation Vsour Imeas Selecting SIVOHMS sets the DMM to 10V range This step closes the channels to make the test connections for the HIPOT test It assumes the single stage inflator is connected as shown in Figure 5 3 This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Performs cable discharge for input channels 1 and 2 and opens all channels This step closes the channels to make the test connections for the second HIPOT test It assumes the dual stage inflator is connected as shown in Figure 5 5 This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Performs cable discharge for input channels 4 and 5 and opens all channels Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 28 Model 2790 SourceMeter Switch System User s Manual I source readback This readback circuit measures the
15. 5 65 65 FAST 300 Hz 300kHz MEASUREMENT METHOD AC coupled True RMS SHUNT RESISTANCE 0 10 BURDEN VOLTAGE 1A 0 3Vrms lt 1 Vrms Add 1 Vrms when used with 7702 modules INPUT PROTECTION 250V fuse HW 11 04 03 Rev D Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications MAINFRAME FUNCTION SPECIFICATION AC System Speeds RANGE CHANGES 4 3 s FUNCTION CHANGES 4 s 3 s AUTORANGE TIME lt 3s ASCII READINGS TO RS 232 19 2k baud 50 s MAX INTERNAL TRIGGER RATE 300 s MAX EXTERNAL TRIGGER RATE 250 s AC Notes 20 overrange except on 750V and 3A Specifications are for SLOW mode and sine wave inputs gt 5 of range SLOW and MED are multi sample A D conversions FAST is DETector BANDwidth 300 with nPLC 1 0 gt Applies to 0 18 and 28 40 C Specifications are for square wave inputs only Input signal must be gt 10 of ACV range If input is lt 20mV on the 100mV range then the frequency must be gt 10 7 5 Applies to non sine waves gt 5Hz and 500Hz Guaranteed by design for Crest Factors 74 3 6 For 1kQ unbalance in LO lead 7 Speeds are for 60Hz 50Hz operation using factory defaults operating conditions RST Autorange off Display off Limits off Trigger delay 0 Includes measurement and binary data transfer out GPIB 0 01 of step settling e
16. 6 5 5 50 40 1 compensation On 5 51 15 100 80 0 1 200 C to 630 C 0 01 C 0 06 C 0 003 C C 5 515 16 250 200 0 1 Thermistor 2 2kQ 5kQ and 10kQ 5 516 480 400 0 1 80 C to 150 C 0 01 C 0 08 C 0 002 C C 4 516 2000 1800 0 01 ee 4W Ohms lt 10 6 55 14 11 10 DC Speed vs Noise Rejection 6 515 15 12 1 RMS Noise 5 516 33 25 0 1 Rate Filter Digits 10 Range NMRR CMRR RTD 655 0 9 07 10 10 50 0 00 0 08 6 5 lt 12 110 dB 120 dB 6 55 8 64 1 1 15 12 6 5 4puV 90 dB 120 dB 5 515 16 18 14 4 0 1 0 1 Off 500 400 5 5 lt 22 uV 80 Channel Ratio 6 515 25 2 10 0 01 Off 2000 1800 45 lt 150 8048 Channel AVG 6 55 15 12 1 5 516 25 20 0 1 HW 11 04 03 Rev D Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications MAINFRAME FUNCTION SPECIFICATION DC System Speeds RANGE CHANGES 50 5 42 5 FUNCTION CHANGES 50 5 42 s AUTORANGE TIME lt 30ms ASCII READINGS TO RS 232 19 2k BAUD 55 5 MAX INTERNAL TRIGGER RATE 2000 s MAX EXTERNAL TRIGGER RATE 375 s DC MEASUREMENT CHARACTERISTICS DC Volts A D LINEARITY 2 0 ppm of reading 1 0 ppm of range INPUT IMPEDANCE 100mV 10V Ranges Selectable gt 10GQ with lt 400pF or 10MQ 1 100 1000V Ranges 10MQ 1 INPUT BIAS CURRENT lt 100pA at 23 C COMMON MODE CURRENT lt 500nA
17. M36 M37 M38 M39 M40 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 3 Keithley 7702 Switching Module e Safety precautions Follow these safety precautions before using the 7751 7752 7753 modules with the 7702 module Using 7751 7753 V source with 7702 module Explains how to use the 7751 7753 V source with the 7702 module Includes a test circuit diagram to explain this application Card configuration Provides the simplified schematic of the Keithley 7702 switching module Summarizes key aspects of the module Typical connections Shows typical module connections for the various measurements Includes a connection log to record connection information and channel descriptions Opening and closing 7702 channels Explains how to open and close channels for the 7702 module e Viewing closed channels Explains how to display closed channels on the Model 2790 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 3 2 Model 2790 SourceMeter Switch System User s Manual NOTE Installation of Keithley switching modules in the mainframe of the Model 2790 is covered in Section 4 Details on using the Keithley 7702 module are provided in the Model 2790 Reference Manual Details on using the ohms functions of the Model 2790 with the
18. Only Max Temperature Source Resistance Short Accuracy Coefficient Voltage Range Current Rdg 0 189 amp 28 40 500V 10MQ ImA 0 8 0 03 500V 100MQ ImA 1 196 0 05 500V 1GQ ImA 4 0 0 12 50V IMQ lt ImA 1 1 0 04 50V 10MO ImA 1 196 0 06 50V 100MQ ImA 1 696 0 13 7753 Only Max Temperature Source Resistance Short Ckt Accuracy Coefficient Voltage Range Current Rdg 0 189 amp 28 40 500V 1 lt ImA 0 8 0 02 C 500V 10MQ lt 1 0 9 0 03 500V 100MQ ImA 1 396 0 10 500V 1GQ ImA 6 7 0 27 50V 0 1MO ImA 1 196 0 03 50V 1 lt 1 1 1 0 04 50V 10MO ImA 1 396 0 11 C 50 100MQ lt ImA 4 5 0 30 C Accuracy 0 5 0 13V 2yr Specification Settling Time Rise Time 50V to 500 step 0 1 of final value 250 ms max Fall Time 500V to 50 step 0 1 of final value 1000 ms max Temperature Coefficient 0 189 amp 28 40 0 001 0 005V C Safety Limit Current limited maximum current of 1 Cable Discharge Ch 20 100kO Shunt Max Capacitance 1nF Current Measure Input 7751 7753 Only Range 7751 0 50uA 7753 0 500pA Accuracy 7751 0 5 of reading 6nA 2yr Specification 7753 0 5 of reading 60nA 2yr Specification Temperature Coefficient 0 189 amp 28 40 0 02 0 5nA C Voltage Burden 1mV Current Source Output Output Level Programmable 0 to
19. Switching Modules Card configuration Provides the simplified schematic of the Keithley 7751 7752 and 7753 switching modules Summarizes the individual components of the modules Setting source output levels Explains how to set the output levels for the I source 7751 7752 7753 and V source 7751 7753 Math Covers the ohms math functions used to calculate low resistance when using the I source of the 7751 7752 7753 and high resistance when using the V source and I V amplifier of the 7751 7753 module Openingand closing channels Explains how to open and close channels for the 7751 7752 and 7753 modules e Viewing closed channels Explains how to display closed channels on the Model 2790 Openinterlock errors Explains the errors associated with an open interlock Cable discharge circuit 7751 and 7753 Explains the cable discharge circuit It dissipates voltage at the input channels This unwanted voltage could ignite the inflator Connection log Use to record connection information Using memory patterns Describes the memory patterns feature which can be used to simplify repetitive test procedures Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 2 Model 2790 SourceMeter Switch System User s Manual NOTE Module wiring and installation into the mainframe of the Model 2790 is covered in Section 4 Details on using
20. Voltage connections DCV or ACV DC Voltage AC Voltage Connection log Make a copy of Table 3 1 and affix it to the cover of the Model 7702 Use this to record connection information and channel descriptions as needed Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Table 3 1 Connection log Model 7702 Channel Color Description Description Color Channel INPUT H L SENSE H L CH21 H H L 15 22 H CH2 L L CH23 H H CH3 L L CH24 H H 4 L E CH25 H H 5 L L CH26 H CH6 L L CH27 H H CH7 L L CH28 H H CH8 L L CH29 H H CH9 L L CH30 H H 10 L L CH31 H H 11 L L CH32 H 2 L L CH33 H CHI3 L L CH34 H H 4 L L CH35 H H 15 L L CH36 H H 16 L L CH37 H H 17 L L CH38 H H 8 L 39 19 L L CH40 H 20 L L AMPS41 H H 542 L L Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 9 Opening and closing 7702 channels Normally system channel operation is
21. VyAs will include the voltage drops across the two test leads Therefore the measured voltage which is used to calculate resistance will not be the same as the actual voltage across RDUT Figure 6 1 Using Q2 function to measure resistance Keithley 2790 Test Current Input HI RLEAD IsOURCE 1mA Q2 Function Selected I VMtAs Voltage measured by 2790 DMM Vr Voltage across RDUT VMEAS RMEAS Rout 2 x RLEAD ISOUR VR ISOUR Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual The 4 wire Kelvin connection method shown in Figure 6 2 should be used for low resis tance measurements With this configuration the test current is forced through through one set of test leads while the voltage is measured through a second set of test leads called sense leads Due to the high impedance of the DMM of the Model 2790 negligible current will flow through the sense leads Since the voltage across the sense leads will be negligible the voltage measured by the DMM is essentially the same as the voltage across the DUT Vp Figure 6 2 Using Q4 function to measure resistance Test Current RLEAD Rout Vmeas Voltage measured by 2790 DMM Vr Voltage across RDUT Because sense current is negligible VR Therefore VMEAS VR Isour IsouR RME
22. actual current that is flowing in the test circuit through the DUT bridgewire or shunt bar It is used to verify that the programmed current level of the I source is being used in the tests NOTE lI source readback is only accurate to 1 It is only intended as a verification and not a high accuracy measurement The I source readback circuits are shown in Figure 5 13 Figure 5 13A shows how to measure the current for the bridgewire test while Figure 5 13B shows how to measure the current for the shunt bar test In both circuits the Model 2790 DMM measures the voltage across the 1Q resistor Readback current Igp is then calculated using Ohms Law Ipp Vmeas 19 Make sure to open all channels before closing the appropriate channels for I source read back When finished make sure to again open all channels The mX b calculation can be used to read the I source current in amps by setting m to 1 0 and b to 0 0 Front panel operation Press SHIFT gt press MATH gt select mX B gt set M to 1 0 gt set B to 0 0 select UNITS A Remote programming CALC FORM MXB CALC KMAT MMF 1 0 CALC KMAT MBF 0 0 CALC KMAT MUN CALC STAT ON Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 5 13 I source readback circuit A g Test Equipment Depot 800 517 8431 99 Washington Street M
23. clist gt Select range 0 to 11 3 100e6 FRESistance RANGe lt clist gt Query 24 range FRESistance OCOMpensated lt b gt lt clist gt Enable or disable offset compensated OFF ohms ON or OFF FRESistance OCOMpensated lt clist gt Query state of OCOMP Suggested parameters SYSTem PRESet and RST disables offset compensated To select 100Q range let lt n gt 100 ohms and selects the 100MQ range for the O4 function To select 1kQ range let n 1 3 To select 10kQ range let n 10e3 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 6 6 Model 2790 SourceMeter Switch System User s Manual Keithley 7702 module The 40 two wire or 20 four wire input channels of the 7702 module make it ideal to test multiple DUT With system channel operation a single channel closure connects a DUT to the Model 2790 DMM for measurement Testing multiple DUT can be further automated using the scanning feature of the Model 2790 Once configured the testing process can be started with a single press of a button or when commanded for remote programming NOTE Details on scanning 7702 channels are provided in Section 7 of the Model 2790 Reference Manual Figure 6 3 shows the simplified test circuit for using the 24 function of the Model 2790 with the 7702 module to measure low ohm DUT The DUT is connected to channels 1 and 21 of the 7702 When channel 1 is c
24. involves hazardous voltages It is the responsibility of the customer to operate instruments in a safe manner Be sure to read and follow the instructions for connecting and wiring the tester in Section 4 before operating the equipment NOTE ensure the reliability of the HIPOT test it should be performed after verifying contact Contact checks and the output of the V source V source readback Single stage inflator Perform Test Steps 1 through 7 in Table 5 6 Dual stage inflator Perform Test Steps 1 through 11 in Table 5 6 Table 5 6 Test procedure HIPOT Test Step Command Sequence Front Panel Operation 1 Reset 2790 and RST Press SHIFT gt press SETUP gt select RESTORE open all channels FACT 2 Set V source to SOUR VOLT 500 128 Press SHIFT gt press CARD gt select CONFIG gt 500 Include 250msec program delay to select SLOT1 7751 or 7753 gt display V C28 gt set allow source to settle to 500 0 V 3 Select and enable CALC1 FORM S1V Press SHIFT press MATH select SIVOHMS the high ohms CALC1 STAT ON calculation 4 Close channels to ROUT MULT CLOS Press CLOSE gt select MULTI gt select 101 gt select perform HIPOT 8101 103 108 116 118 103 gt select 108 gt select 116 gt select 118 gt select test 121 122 123 121 gt select 122 gt select 123 gt press EXIT 5 Verify channels ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select that are c
25. is connected to Bank 1 of a 7751 7752 or 7753 Channel 124 is closed before channel 121 so that the clamp is in place before connecting source to signal backplane Channels are closed in order listed This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 14 Model 2790 SourceMeter Switch System User s Manual Bridgewire tests NOTE interlock of the 7751 7752 7753 must be enabled to use the I source Figure 5 6 shows how interlock is enabled Test circuit The circuit for an inflator bridgewire test is shown in Figure 5 8 Figure 5 8 Test circuit bridgewire tests 21 1 or 4 4 17 18 Bridgewire Under 2790 DMM Input LO Test Closed channel switch Test assumptions To test bridgewire connected to Bank 1 close input channels 1 and 2 To test bridgewire connected to Bank 2 close input channels 4 and 5 NOTE Each channel is a 2 pole switch Therefore when a channel is closed two switches close see schematic in Figure 2 1 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Test pr
26. module However the test current used by the Model 2790 is fixed For the 100 and 1kQ ranges the test current is fixed at ImA Low ohms accuracy comparison When using the current source of the 7751 7752 or 7753 module to perform 4 wire low ohms measurements accuracy is 0 09 50mA For the Model 2790 when using the 24 function 4 wire ohms 10002 range and offset compensation basic resistance measurement accuracy is 0 0196 1 year spec Fuse resistance considerations Two fuses F3 and F4 are in series with the output of the on card current source to insure that the test current cannot exceed 62mA Fuses F1 and F2 are in series with the backplane connection to the meter INPUT HI For DMM resistance measurements these fuses are in series with the mainframe current source similar to F3 and F4 these fuses limit the main frame current output to a maximum of 62mA Because fuses F1 and F2 are in series with the DMM output they appear as lead resistance a 2 wire measurement As a result the measured value of a short circuit connected to channels 1 2 4 5 7 8 10 or 11 and measured with the DMM in 2 wire ohms will basically equal the resistance of these fuses plus any additional trace and lead resistance The nominal cold resistance of a single fuse is about 5 50 Therefore when you measure a short through the 7751 7752 7753 modules using the DMM 2 wire ohms function for example contact checks you will actually
27. read two times the fuse resistance plus any trace and other lead resistance The resistance of these fuses is fairly temperature sensitive Typically a short measured right at the channel terminals reads between 120 cold to approximately 15 2 hot Although not usually a problem you can correct for this offset using the REL function of the DMM subtract the offset from the readings in your test pro gram or you can simply adjust pass fail limits NOTE Fuse resistance does not affect 4 wire measurements which sense around the lead resistance Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 6 3 High ohms measurements The 7751 and 7753 include a programmable V source 50 to 500V so the constant volt age method can be used to measure high resistance such as insulation resistance The Model 2790 mainframe does not have a voltage source If not using a 7751 or 7753 module in your test system you can use the Q2 function 100 range of the Model 2790 to measure insulation resistance up to 120MQ 4 wire ohms 4 wire ohms eliminates the effects of test lead resistance when measuring a low ohms DUT Figure 6 1 shows how 2 wire ohms can be adversely affected when measuring a low ohms DUT If the test lead resistance Ry is relatively large in comparison to the resistance of the DUT the measured voltage
28. reading from display Press OPEN gt select ALL Test step notes 1 Resetting the 2790 opens all channels and selects the function auto range For remote programming RST places the 2790 in the one shot trigger mode For front panel operation FACT defaults places the 2790 in the continuous trigger mode Un BW Always open all channels at the beginning and end of a test Cable discharge This step closes the channels to connect the V source output to the DMM of the Model 2790 This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading After using the V source of the 7751 7753 module a charge may be stored in the test cables and module signal paths The resulting voltage could ignite the inflator if it is con nected across a bridgewire Therefore a cable discharge circuit is used to safely dissipate the charge In brief cable discharge is automatically implemented when the OPEN ALL operation is performed As long as the test cables are connected to the module and the input channels 1 channels 1 and 2 are closed all stored energy in the circuit will dissipate safely NOTE Details on the cable discharge circuit are provided in Section 2 NOTE The test procedure for HIPOT uses the OPEN ALL operation to perform cable discharge see steps 7 and in Table 5 6 NOTE For high ohms measurement
29. safety features to reduce the possi bility of inflator ignition and damage to the module due to excessive current Interlock The interlock feature of a 7751 7752 7753 module disconnects the sources I source and V source from the switching matrix Details on the interlock are provided in Section 5 Fuses Current limiting fuses for the current source of the Model 2790 DMM and the I source of the 7751 7752 7753 module source current limiting An active high speed current limiting circuitry for the I source of the 7751 7752 and 7753 modules e V source current limiting An impedance circuit limits current to 1mA Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 1 3 Technical terms The following defines and explains technical terms associated with airbag inflators Initiator Pyro technic device used to trigger the main gas charge generation action Sometimes referred to in classic military terms as a squib The term squib may be used to refer to the core element of an initiator explosive coated bridgewire or to the entire initiator Airbag inflator The gas generating assembly typically made of steel contain ing a stored chemical or pressurized inert gas or both and an electrical initiator Hybrid inflator An inflator that uses both pressurized gas and a chemical reaction
30. sequence closes channel 1 for a 7751 7752 7753 installed in slot 1 Press CLOSE gt select MULTI gt select 101 gt press EXIT What the sequence means is Press CLOSE Press the CLOSE key select MULTI Use the edit keys up or down key to display the MULTI menu option and press ENTER select 101 Use the edit keys up down left or right arrow keys to display chan nel 101 and press ENTER press EXIT Press the EXIT key to exit the menu Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 3 Closed channels for test circuits Test circuits show which channel switches need to be closed to make the test connections Keep in mind that these and only these channels must be closed for the test All other channels in the system must be open As a rule ALWAYS open all channels at the begin ning and end of a test NOTE To use the DMM of the Model 2790 to measure a DUT connected to a switching module the front panel INPUTS switch must be in the REAR in position Test system Figure 5 1 shows a typical test system and connections using a programmable logic con troller PLC or a PC Connections for the test signals and interlock are covered in Test signal connections NOTE one Model 7753 can be installed in a Model 2790 and it should be installed in slot 1 A 7753 module can be used in slot 2 but measurement
31. source tracking Programming errors 222 Parameter out of range Attempted to select a source SOURCe command with a 7702 card installed 241 Hardware missing Attempted to select a source SOURCe command that is not installed 870 Invalid current error Attempted to track I source that is set to For the low ohms calculation m 1 I oug Dividing 1 by 0 would result an erroneous reading positive infinity Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 13 Opening and closing channels Multiple channel operations are used to control 7751 7752 and 7753 channels Only the specified channels are opened or closed Unspecified channels are not affected Relays to connect signals to the backplane DMM of the Model 2790 do not close automatically You must explicitly close them to perform a measurement For example with a DUT connected to channel 1 of a 7751 7752 or 7753 module you would have to close channels 1 14 and 18 to measure it with the Model 2790 Closed channels are not displayed by the Model 2790 while in the normal display state Closed channels can be viewed from the VIEW item of the CARD menu see Viewing closed channels for details To control the appropriate switching module the slot number must be included with the switching module channel number The
32. the Keithley 7751 7752 7753 modules to test inflators are provided in Section 5 The edit keys left right up and down arrow keys are used to display menu items and output levels With the desired menu item or output level displayed it is selected by pressing ENTER For remote programming the lt clist gt parameter is used as follows lt clist gt SCH where S Mainframe slot number 1 or 2 CH Switching module channel number of source 2 digits Examples 101 Slot 1 Channel I 49101 114 118 Slot 1 Channels 1 14 and 18 Card configuration CAUTION External energy sources should never be applied directly to a 7751 7152 or 7753 module for any reason Damage to the module and any connected devices under test can result due to the application of improperly selected or performing external energy sources The simplified schematic for the 7751 7752 and 7753 is provided in Figure 2 1 Channels 1 12 Input channels for DUT inflator Channels 13 19 and 25 Routes test signals to backplane of Model 2790 Channels 20 24 27 and 28 Control individual components of the 7751 7752 7753 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com witc stem Users anua Model 2790 5 Meter Switch System User s Manual 2 3 Figure 2 1 Simplified schematic of Keithley 7751 7752 and 7753 switching modules Ch 25
33. the responsibility of the customer to operate instruments in a safe manner Be sure to read and follow all installation and operating instructions before attempting to use the 7751 7753 HIPOT function There are three basic tests for insulation resistance Two preliminary verification tests and the HIPOT test e Contact checks These checks use the ohmmeter of the Model 2790 to verify that the V source test circuit is properly connected to the inflator housing and the bridgewire e V source readback This test uses the voltmeter of the Model 2790 to measure the actual output of the V source This test should be done before every HIPOT test to ensure that the programmed voltage is being used e Cable discharge Summarizes cable discharge which is used to dissipate energy stored in the test cables and the module by the V source e HIPOT test This test measures the insulation resistance of the inflator Single stage inflator connections to the 7751 7753 module are shown in Figure 5 3 while dual stage inflator connections are shown in Figure 5 5 These connections accommodate all three tests for insulation resistance NOTE The interlock of the 7751 7753 must be enabled in order to use the V source Figure 5 6 shows how interlock is enabled Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Contact checks NOTE Low re
34. to generate the gas charge for bag inflation Airbag or Airbag module The fully functional device including initiator inflator textile bag and mounting frame or enclosure E check Industry standard term for electrical testing of airbag inflators and modules Consists of two basic resistance measurements Test continuity of the bridgewire typically 2 to 3 ohms using a constant current method typically 10 to 50mA test Measure the insulation resistance 2100M 2 between the bridgewire and the inflator housing using an applied voltage typically 500V HIPOT Used in this manual to describe the high resistance measurements made using high voltage The intent is not to break down the insulator but to measure the leakage current that flows through the insulator Body check contact check Prior to HIPOT testing connections to the inflator housing must be verified This is necessary because an open connection would result in a reading that appears to be the resistance of the insulator but would instead be a high resistance reading that is the result of an open circuit Shorting clip shunt bar For handling and transport safety against ESD electro static discharge or other accidental discharge every inflator module has a spring loaded clip that shorts the initiator squib pins together when a connector is not installed The connection cables also include shorting clips since many inflator module
35. used to control 7702 input channels NOTE Itis not recommended but multiple channel operation can be used to control a 7702 module For multiple channel operation the 7702 module is controlled in basically the same way that a 7751 7752 7753 module is controlled see Section 2 except that multiple channel control ROUT MULT must be used to control the 7702 module More details on multiple channel operation is provided in Section 2 of the Model 2790 Reference Manual The following points summarize system channel operation Details on system channel operation for the 7702 module is provided in Section 2 of the Model 2790 Reference Manual When an input channel is closed for a 2 wire function a backplane isolation chan nel automatically closes to connect the input to the DMM of Model 2790 Example With the 22 function selected closing channel 1 also closes channel 45 When an input channel is closed for a 4 wire function or operation the two back plane isolation channels and the 2 pole 4 pole relay also close to connect the input to the DMM Example With the 24 function selected closing channel 1 also closes channel 21 paired channel 45 backplane channels and 43 2 pole 4 pole relay While in the normal measurement display state only the input channel that is closed is displayed on the Model 2790 For a 4 wire operation the paired input channel is not displayed Only one input channel and its paired input channel for 4
36. 0 SourceMeter Switch System User s Manual Figure 4 4 Wire dressing 7751 7752 7753 SOURCE SENSE HI LO HI LO 909999 99 9 9 Soo geen 9 9 99596999 000000 LO SRG SEN SRC SEN A Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com 4 8 Model 2790 SourceMeter Switch System User s Manual Zippertubing shield A grounded wrap around shield for the wiring between the switching module and the test station should be installed The shield is a grounded metal foil that surrounds the bundle of wires The foil shield prevents damage to the wire insulation Grounding the shield to a safety earth ground provides extra protection in case a wire conductor becomes exposed It also serves to reduce measurement noise caused by EMI from nearby machinery A recommended shield is shown in Figure 4 5 It is a Zippertubing ZTZ SH3 series shield As shown the foil side wraps around the cable wires The shield is then held in place by fastener strips that zip together The ground wire of the shield is to be connected to a safety earth ground as shown in Figu
37. 01A lt clist gt 127 Slot 1 227 Slot 2 AMPLitude lt clist gt Query I source output level Note Selecting an ohms calculation enables source tracking Selecting any other math function disables source tracking Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 9 Math There is a shortcut math function to calculate low resistance when using the I source of a 7751 7752 7753 module and one to calculate high resistance when using the V source and I V amplifier of a 7751 7753 module Low ohms calculation Sxlohms e Sxlohms Calculates and displays low resistance reading for 7751 7752 7753 module in slot x where x 1 or 2 This ohms function is a shortcut for the mX b calculation When selected the following and b factors are used m 1 Isour b 0 Calculation R mX b 1 Isour X 0 ISOUR 11 where is the programmed current level of the I source of the 7751 7752 or 7753 1 Isour is the m factor for the calculation mX b Vmeas Is the voltage measured by the DMM of the Model 2790 It is the X variable for the calculation mX b When the SxIohms calculation is selected the Model 2790 measures voltage X and calculates mX b using the above factors The displayed reading will be in ohms Q This selection also sets DMM to
38. 1 7752 7753 and Table 3 1 for the 7702 and affix it to the module cover 6 Close and lock cover Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 4 2 Model 7751 7752 7753 screw terminal channel designations SOURCE SENSE GUARD HI LO HI LO 4 5 J101 Input channels 1 3 J102 Input channels 4 6 r BANK 1 2 SRC SEN SRC SEN 1 Bi SRC SEN SRC SEN A2 B2 HI HI LO LO HI HI LO LO o c 3 EHE 96699 9 Ire TT SOURCE SENSE GUARD HI LO HI LO 9 QO 2 SRC SEN SRC A2 B2 HI LO fo peeo 196 9 oo o o 0 Lr 14 079 QO INT 5V INT LO HI LO VSOURCE ISOURCE GUAJ INTERLOCK f Hd 011 D Q Q0 Q0 00 HI LO HI LO OUT LO 1 VSOURCE ISOURCE GUARD ad Ch7 HI HI LO LO SRC SEN SRC SEN BANK 3
39. 176 TestEquipmentDepot com 6 2790 Ohms Functions Introduction Summarizes the differences between the methods used by the Model 2790 DMM and the 7751 7752 7753 modules to measure resistance 4 wire ohms Explains the benefits of using the 4 wire ohms technique to measure low resistance Offset compensated ohms Explains the offset compensated ohms feature which is used to cancel the adverse effects of offset voltages present in the test circuit Keithley 7702 module Shows how to use the ohms functions of the Model 2790 DMM with the 7702 module e Keithley 7751 7752 and 7753 modules Shows how to use the ohms functions of the Model 2790 DMM with the 7751 7752 7753 module Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 6 2 Model 2790 SourceMeter Switch System User s Manual Introduction As a general rule for testing inflators the programmable I source of the 7751 7752 7753 modules should be used to measure low resistance bridgwires and shunt bars The pro grammable V source of the 7751 7753 module should be used to measure insulation resis tance For other resistance measurements wiring harnesses fuse blocks switches relays etc an ohms function Q2 or 4 of the Model 2790 can be used Low ohms measurements The ohms functions of the Model 2790 provide better accuracy than the I source method used by the 7751 7752 7753
40. 20kQ where is the voltage output setting in volts Example Determine ohms accuracy for a V source setting of 100V of reading 1 1 60 100 1 1 0 6 96 1 796 Ohms accuracy 100V 1 7 20kQ Ohms temperature coefficient TC of reading 0 02 6 VsouRcE 1 ohms offset 2000 C where Vsourceg is the voltage output setting in volts Example Determine temperature coefficient for a V source setting of 100 of reading 0 02 6 100 96 C 0 02 0 06 C 0 08 C Ohms temperature coefficient 100 0 08 2000 C Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Specifications 11 For measurements 100MQ to 1GQ Ohms accuracy of reading 2 510 VsourcE Ohms offset 20kQ where Vsourcg is the voltage output setting in volts Example Determine ohms accuracy for a V source setting of 100V of reading 2 510 100 2 4 5 1 96 7 196 Ohms accuracy 100V 7 1 20kQ Ohms temperature coefficient TC of reading 0 02 51 Vsourcr TC ohms offset 2000 C where is the voltage output setting in volts Example Determine temperature coefficient for a V source setting of 100V of reading 0 02 51 100 9o C 0 02 0 51 C 0 53 C Ohms temperature c
41. 26 e CH11 and CH31 CH16 and CH36 e CH2 22 CH7 CH27 e CH12 2 CH17 CH37 e CH3 23 CH8 CH28 e CH13 CH33 18 CH38 e CH4 and CH24 CH9 and 29 CH14 and CH34 CH19 and CH39 e CH5 25 10 5 5 20 CH40 Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 3 1 Simplified schematic of Keithley 7702 switching module LO Input LO Sense O O O O E 01 Channel 1 LO Channels 2 19 o o HI Channel 20 LO Channel 43 2 Pole Open Qo 4 Pole Closed see Note O O Channel 21 Channels 22 39 o oT o o HI O a Channel 40 LO O 3A Channel 41 LO o Oo 3A od Channel 42 LO O O Channel 45 see Note Backplane Isolation oO Input O O Channel 44 see Note Backplane Isolation o oHI To Model Sense 2790 Backplane AMPS Note Channels 43 45 in this schematic refer to the designations used for control and not actual available channels Channels 43 44 and 45 can be individually controlled using multiple channel operation ROUT MULT commands if the module is not to be co
42. 5 Inflator Testing Figure 5 1 System COMMECHONS 5 3 Figure 5 2 Test connections shunt bar bridgewire testing single stage inflator 2222 5 5 Figure 5 3 Test connections shunt bar HIPOT and bridgewire testing single stage inflator sse 5 6 Figure 5 4 Test connections shunt bar and bridgewire bar testing dual stage inflator see 5 7 Figure 5 5 Test connections shunt bar HIPOT and bridgewire testing dual stage inflator sse 5 8 Figure 5 6 Interlock connections rece treni e 5 9 Figure 5 7 Test circuit sh nt Dar t ett 5 11 Figure 5 8 Test circuit bridgewire tests 222 22 5 14 Figure 5 9 Test circuits contact check single stage inflator 5 19 Figure 5 10 Test circuits contact check dual stage inflator 5 19 Figure 5 11 V source readback circuit esee 5 22 Figure 5 12 Test circuit BIPOYT 2s e e erp euo 5 25 Figure 5 13 I source readback Circuit teer edt 5 29 Figure 5 14 Test circuits memory patterns dual stage inflator contact test 5 30 6 Model 2790 DMM Ohms Functions Figure 6 1 Using W2 function to measure resistance 6 3 Figure 6 2 Using W4 function to measure resistance 6 4 Figure 6 3 Using Model 2790 4 wire ohms with
43. 50mA Ch 27 Programming Resolution 104A Output Voltage 5 5V 10 compliance Accuracy 0 06 10uA 2 yr Specification Settling Time 1115 to 0 1 of final value typ Temperature Coefficient 0 18 amp 28 40 0 001 0 25pA C Dry Circuit Clamp Ch 24 20mV 10 Isource lt 1 Switching Capabilities Bank 1 Bank 4 4 Channels 1 Form A switch 8 Channels 4 4 pole or 8 2 pole signals into DMM or I V converter Contact Check 4 Wire contact check through internal DMM Relay Type Latching electromechanical Actuation Time lt 3ms Contact Life typ gt 10 operations at maximum source level gt 10 operations cold switching Contact Resistance lt 1 Ohm at end of contact life Contact Potential lt 42uV typical per contact pair 3uV max Connector Type Plugable screw terminal 22 AWG wire size Isolation Between two Terminals gt 1 lt 100 Isolation Between Terminals and Earth gt 1GQ lt 200 Isolation Between Channel Groups gt 500GQ 100pF External Common Mode Voltage 42V between any terminal and chassis Connect no external sources 7751 7752 or 7753 Module Notes Isolation for channels 1 12 only one channel closed at a time or all channels open 2 See User s manual for ohm specifications at sources other than those specified 3 All specifications valid for 1 NPLC ADC aperture setting Voltage Source Output 7751 7753 Only Ou
44. 753 module from its built in I source and V source However if an external source such as the 12V car bus is connected to the front panel inputs of the Model 2790 or through a 7702 module these safety features are compromised creat ing the very real possibility of igniting the airbag Incorrect channel clo sures in the test system could inadvertently apply the external source to the inflator and ignite it Damage to the 7751 7752 7753 module may also occur if an external source is connected to it Since the Model 2790 system is not an intrinsically safe device it is the responsibility of the user to ensure that external protection be pro vided either by an inherently safe electrical barrier and or a safety bar rier around the DUT or airbag to prevent injury in case of detonation Setting source output levels I source and V source 7751 7753 output levels are set from the CONFIG item of the CARD menu The menu structure shown in Figure 2 2 is accessed by pressing and releasing SHIFT and then pressing CARD source Set output from 0 to 50mA In the menu structure the I source is desig nated as channel 27 The default setting is ImA e V source 7751 7753 only Set output from 50 to 500V In the menu structure the V source is designated as channel 28 The default setting is 50V NOTE When using the V source as an independent source limit 7751 output current to 50uA or 7753 output current to 5004A to achieve rated acc
45. 7702 module low ohms measurements sess 6 6 Figure 6 4 Using Model 2790 2 wire ohms with 7702 module high ohms measurements see 6 7 Figure 6 5 Using Model 2790 4 wire ohms with 7751 7752 7753 module low ohms measurements 6 8 Figure 6 6 Using Model 2790 2 wire ohms with 7751 7752 7753 module high ohms measurements esse 6 9 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com List of Tables 2 Keithley 7751 7752 and 7753 Switching Modules Table 2 1 Commands to set amplitude for V source and I source 2 8 Table 2 2 Commands to select ohms calculations 2 12 Table 2 3 Commands to control 7751 7752 7753 module channels 2 14 Table 2 4 Connection log Model 775 1 7752 7753 2 19 Table 2 5 Basic memory pattern example sese 2 22 Table 2 6 Memory pattern log cnc etre eet 2 23 3 Keithley 7702 Switching Module Table 3 1 Connection log Model 7702 3 8 Table 3 2 Commands to control 7702 module channels 3 11 5 Inflator Testing Table 5 1 Test procedure shunt 5 13 Table 5 2 Test procedure bridgewire 22 1 2 5 15 Table 5 3 Test procedure contact checks for single stage inflator 5 20 Table 5 4 Test procedure contact c
46. 7702 module are provided in Section 6 The edit keys left right up and down arrow keys are used to display menu items and output levels With the desired menu item or output level displayed it is selected by pressing ENTER For remote programming the lt clist gt parameter is used as follows lt clist gt SCH where S Mainframe slot number 1 or 2 CH Switching module channel number of source 2 digits Examples 201 Slot 2 Channel I 201 214 218 Slot 2 Channels 1 14 and 18 201 210 Slot 2 Channels 1 through 10 Safety precautions In a system to test inflators a 7702 module may be used with the 7751 7752 or 7753 module In a mixed module configuration like this the following safety precautions must be understood and taken External energy sources should never be applied directly to a 7751 7752 or 7753 module for any reason Damage to the module and any connected devices under test can result due to the application of improperly selected or performing external energy sources Additional precautions should be taken when using the mainframe measurement functions for the 7751 7752 7753 modules and an external source connected through the Model 7702 switch module In the case of a single hardware or software configuration error or in a fault condition external energy sources can become directly connected to unintended device under test connections Where this possibil ity exists it is the system d
47. 7752 and 7753 Switching Modules Card conbe ratioD serere re ee ete e ts 2 2 I source channels 21 22 24 and 27 2 4 V source and I V amplifier 7751 7753 only channels 21 2223 28 EGER 2 4 Cable discharge 7751 7753 only channel 20 2 4 Source readback channels 13 and 25 2 5 Interlock 1106 om eoe aenean 2 5 General purpose terminal blocks J105 J107 and J108 2 5 Safety WAEPungs uaa esci ie tede 2 6 Setting source output levels eee 2 6 Remote programming eene 2 8 IET RT 2 9 Front panel operation 2 2 rte eterne 2 11 Remote programming 2 11 Opening and closing channels 2 13 Front panel operation eec iet 2 13 Remote programming eene 2 14 Viewing Closed channels eere 2 15 Open interlock errors 1 tete eroe 2 16 Cable discharge circuit 7751 and 7753 2 17 Connection log oup e e Rr 2 19 Using memory patterns teeth tiet etse 2 20 Firmware revision level oce 2 20 OVERVIEW M 2 20 Front panel operation ert rettet 2 20 Memory pattern commands eee 2 21 Setting up and executing memory patterns
48. 7752 7753 and 7702 modules Figure 4 4 shows how to wire a 7751 7752 7753 module Wiring for the 7702 module is similar WARNING not connect 7751 7753 V source Hi to earth ground The 7751 7752 7153 module uses a floating ground This floating ground is not connected to safety earth ground Not only will it create a shock hazard by floating up to 500V it will also effectively connect a 1nF capacitor across the V source providing energy storage that could ignite an airbag under fault conditions WARNING All wiring and supplementary insulation must be rated for the maxi mum voltage in the system For example if 500V is being used in the test system the module wiring for both slots must be rated for at least 500V CAUTION For the 7751 7753 be sure not to dislodge the thermal pad on the volt age source Also be sure to use only the top cover with the integral heat sink to assure proper voltage source operation Make sure all power is discharged from the switching module Access the screw terminals see Figure 4 1 Using a small flat blade screwdriver loosen terminal screws and install wires as desired Figure 4 4 shows 7751 7752 7753 connections to channels 1 2 and the interlock 4 Route wire along wire path and secure with cable ties as shown Note that the wires leading out of the module should be encased in a ground wrap see Zippertubing shield 5 Fillin a copy of the connection log Table 2 4 for the 775
49. AS Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 6 5 Offset compensated ohms The presence of thermal EMFs can adversely affect low resistance measurement accuracy To overcome these unwanted offset voltages you can use offset compensated ohms OCOMP Offset compensated ohms performs two measurements using two differ ent test currents The two readings are then averaged to yield a single resistance reading NOTE Details on offset compensated ohms are provided in Section 3 of the Model 2790 Reference Manual Offset compensated ohms measurements can be performed on the 1000 1k and 10kQ ranges for the 4 function Front panel operation Perform the following steps to enable offset compensated ohms 1 Press 04 to select the 4 wire resistance function annunciator on 2 Use the RANGE up and down keys to select the 1000 1k or 10k range 3 Press and release SHIFT and then OCOMP to enable offset compensated ohms OCOMP annunciator on Remote programming The commands to control offset compensated ohms are listed in Table 6 1 Table 6 1 Commands to set offset compensated ohms Commands Description Default SENSe 1 FUNCtion FRESistance lt clist gt Select 4 wire ohms function Q4 FUNCtion lt clist gt Query function FRESistance RANGe lt n gt lt
50. Closing a single channel B Closing multiple channels Press CLOSE key Press CLOSE key Display SINGLE option Display MULT option CLOSE MULT and press ENTER CLOSE MULT and press ENTER CLOSE SINGLE i Specify channel number Specify channel number CLOSE MULT XXX yyy ENTER CLOSE CH and press ENTER ena andl press Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 11 OPEN key As shown in Figure 3 8 the OPEN ALL option of the OPEN key opens all channels in the mainframe both slots while OPEN MULT opens multiple selected channels NOTE For a7751 7752 7753 module the OPEN ALL operation will not open channel 20 if the interlock is open Figure 3 8 OPEN key OPEN CLOSE Press OPEN key Display ALL option Display MULT option and press OPEN again and press ENTER OPEN ALL OPEN MULT OPEN MULT XXX Display channel number XXX and press ENTER Remote programming The commands to control 7702 channels are listed in Table 3 2 Table 3 2 Commands to control 7702 module channels Commands Description ROUTe CLOSe lt clist gt Specify one input channel to close ROUTe OPEN lt clist gt Open channel specified in list ROUTe OPEN ALL Open all channels ROUTe CLOSe Return closed channel ROUTe CLOSe STATe lt clist gt Query channels in specified list 0 open cl
51. DCV 1V range NOTE Sxlohms cannot be selected if the I source is set to 0mA Since 1 Isour dividing 1 by 0 would result in an erroneous reading positive infinity When using the low ohms calculation the highest DCV measurement range that can be selected is 1V Attempting to select a higher range will cause error 222 Parameter out of range Attempting to turn Autoranging on generates error 221 Settings conflict over the GPIB or a AUTORANGE message on the display if done from the front panel AUTO key Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 10 Model 2790 SourceMeter Switch System User s Manual High ohms calculation SxVohms e xVohms Calculates and displays the high resistance reading for the 7751 7753 module in slot x where x 1 or 2 This ohms function is a shortcut for the m X b calculation When selected the following and b factors are used m 200 000 x 7751 m 20 000 x Vsour 7753 b 0 7751 calculation m X b 200 000 X Vsour VMEAS 0 VsouR VMEAS X 200 000 7753 calculation m X b 20 000 X Vsour VMEAS 0 VsoUR VMEAS X 20 000 where Vgoup is the programmed voltage level of the V source of the 7751 7753 For the 7751 200 000 x Vsoug is the m factor for the calculation m X b 200 000 is the value of the feedback resistor for the I V ampli
52. Hz 10 Hz 3 kHz 3 kHz 5 kHz Current 1 000000 A 1 0 uA 90 Day 1 Year 0 30 0 04 0 10 0 04 0 14 0 04 3 000004 10 pA 0 35 0 06 0 15 0 06 0 18 0 06 Temp Coeff C 0 035 0 006 0 015 0 006 0 015 0 006 3 Hz 500 kHz 333 ms 2 us Frequency 100 mV 0 333 ppm 90 Day 1 Year 80 ppm 0 333 ppm SLOW 1s gate and Period to 3 33 ppm 80 ppm 3 33 ppm MED 100ms gate 750 V 33 3 ppm 80 ppm 33 3 ppm FAST 10ms gate Additional Uncertainty of reading Frequency and Period Low Frequency Uncertainty MED FAST MEASUREMENT METHOD Reciprocal Counting technique 20Hz 30Hz 0 3 GATE TIME SLOW 15 MED 100ms and FAST 10ms 30Hz 50Hz 0 50Hz 100Hz 0 10 AC General 100Hz 200Hz 0 0 18 AC CMRR 70dB 200Hz 300Hz 0 0 10 MAXIMUM CREST FACTOR 5 at full scale gt 300Hz 0 0 VOLT HERTZ PRODUCT lt 8 x 10 CREST FACTOR 1 2 23 3 4 AC OPERATING CHARACTERISTICS 0 Additional Uncertainty 0 05 0 15 0 30 OPERATING CHARACTERISTICS 60Hz 50Hz Operation AC MEASUREMENT CHARACTERISTICS Function Digits Readings s Rate Bandwidth ACV ACI 6 5 2s Reading SLOW 3 Hz 300kHz AC Volts 65 1 4 1 1 MED 30 Hz 300kHz MEASUREMENT METHOD AC coupled True RMS 83 48 MED 6 5 35 28 FAST 300 Hz 300kHz INPUT IMPEDANCE 1MQ 2 by lt 100 6s 1 D SLOW 3Hz30kHz INPUT PROTECTION 1000Vp or 400VDC 300Vrms with 7702 Period x module 242 9 9 30 Hz 300kHz 4 5 35 35 FAST 300 Hz 300kHz AC Current 4
53. LWAYS open all channels in the test system at the beginning and end of each test Table 5 3 Test procedure contact checks for single stage inflator Test Step Command Sequence Front Panel Operation 1 Reset 2790 and RST Press SHIFT gt press SETUP gt select RESTORE open all channels FACT 2 Select Q2 SENS FUNC RES Press Q2 3 Close channels to ROUT MULT CLOS Press CLOSE select MULTI select test HI contact 8101 114 118 101 gt select 114 gt select 118 gt press EXIT 4 Verify channels ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select that are closed SLOTI 7751 or 7753 Press EXIT when finished optional 5 Perform READ Take reading from display measurement 6 Open all channels ROUT OPEN ALL Press OPEN select ALL 7 Close channels to ROUT MULT CLOS Press CLOSE select MULTI select test housing 8108 115 118 108 gt select 115 gt select 118 gt press EXIT contact 8 Verify channels ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select that are closed SLOTI 7751 7752 or 7753 Press EXIT when optional finished 9 Perform READ Take reading from display measurement 10 Open all channels ROUT OPEN ALL Press OPEN select ALL Test step notes 1 ta HWP Resetting the 2790 opens all channels and selects the function auto range For remote programming RST places th
54. NING 7702 module is designed to handle DC peak voltages up to 300V generated by external and potentially unlimited energy type sources When the 7702 module is used in conjunction with the 7751 7753 mod ule it can be used safely up to the full output voltage capability of the 7751 7753 V source 500V DC peak This DOES NOT imply that the 7702 module can be used with EXTERNAL SOURCES i e non 7751 7153 derived above 300V DC peak NOTE Although the 7702 module is rated for 300V it can be used with the 500V output from the 7751 7753 module due to the extremely low current available from the source No safety or reliability issues will result from using the 7751 7753 out put with the 7702 module if the equipment is used according to the instructions provided The V source of the Model 7751 7753 can be used with the 7702 module A typical test system is to use the Model 7702 as a dual multiplexer to bias and measure up to 20 DUTs The V source of 7751 7753 module powers the DUT while the DMM of the Model 2790 measures the output of the DUT To prevent overloading of the V source each DUT is powered and measured separately Figure 3 10 shows the test circuit for this application The 7751 V source is connected to the Sense terminals of the 7702 module DUTS are connected to channels 1 through 20 of the 7751 7753 module Channels 21 through 40 are used to connect the V source to each DUT To use the 7702 module as a dual multiplexer
55. NTER key to pause and resume scrolling e Press EXIT to return to the normal display state NOTE For remote programming closed channels can be identified using ROUT MULT CLOS and ROUT MULT CLOS STAT see Table 2 3 Figure 2 5 Viewing closed channels Press Press Select SLOTx 77xx 101 114 118 SLOTx Slot1 or Slot2 Select module 77 7751 7752 7753 Shows channels 101 114 and 118 closed 7753 should be installed in slot 1 for rated accuracy Closed channels scrolled Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 16 Model 2790 SourceMeter Switch System User s Manual Open interlock errors The 7751 7752 and 7753 modules have an interlock When the interlock is open disabled the I source 7751 7752 and 7753 and V source 7751 and 7753 are disconnected from the switching matrix Details on enabling the interlock are explained in Section 5 The fol lowing errors are associated with an open interlock Front panel messages INTRLCK OPEN is displayed briefly if you attempt to close channel 18 19 or 21 with interlock open With the INPUTS switch in the REAR position in readings will overflow OFLO when the interlock is open In the case of the OFLO readings for open interlock the IL1 or IL2 message will also be displayed IL1 is displayed for a slot 1 violation and IL2 is displayed for a slot 2 violation In the c
56. O Source Sense CH3 Al Bl CH4 Source Sense Bank 5 LO Source 2 Sense CH6 A2 B2 CH7 HI Source Sense Bank CH8 LO Source 3 Sense CH9 A3 B3 CH10 HD Source Sense Bank CH11 LO Source Sense 12 4 4 Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com 2 20 Model 2790 SourceMeter Switch System User s Manual Using memory patterns Firmware revision level Memory patterns are supported in Model 2790 units with firmware A04 and higher The firmware revision level is displayed as part of the power up cycle Overview Most Model 7751 7752 7753 tests follow the same basic procedure select a source and set its level configure the Model 2790 measurement close the necessary relays and take a read ing Memory Patterns simplify this process allowing you to store combinations of multiple closed channels source settings and DMM measurement configurations in nonvolatile memory Up to 40 such Memory Patterns designated M1 through 40 be stored There is also memory pattern MO which is defined as an all open pattern Recalling MO opens all channels and resets all sources to their factory default values Similar to closing one 7702 channel and taking a reading you can recall an individual Memory Pattern to close multiple channels and take a reading More importantly you can include Memory Patterns in a scan list and cau
57. OS Press SHIFT gt press CARD gt select VIEW gt select closed optional SLOT1 7751 or 7753 Press EXIT when finished 5 Perform measurement READ Take reading from display 6 Open all channels ROUT OPEN ALL Press OPEN select ALL 7 Close channels to test HI ROUT MULT CLOS Press CLOSE gt select MULTI gt select contact for bridgewire B 8104 114 118 104 gt select 114 gt select 118 gt press EXIT 8 Verify channels that are ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select closed optional SLOT1 7751 or 7753 Press EXIT when finished 9 Perform measurement READ Take reading from display 10 Open all channels ROUT OPEN ALL Press OPEN gt select ALL 11 Close channels to test ROUT MULT CLOS Press CLOSE gt select MULTI gt select housing contact 8108 115 118 108 gt select 115 gt select 118 gt press EXIT 12 Verify channels that are ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select closed optional SLOTI 7751 7752 or 7753 Press EXIT when finished 13 Perform measurement READ Take reading from display Reading should be 29 or less 14 Open all channels ROUT OPEN ALL Press OPEN select ALL Test step notes f 10 11 12 13 14 Resetting the 2790 opens all channels and selects the function auto range For remote programming RST places 2790 in the one shot trigger mode For fro
58. SourceMeter Switch System User s Manual 2 11 Front panel operation An ohms math function is enabled from the MATH menu which is accessed by pressing and releasing SHIFT and then MATH see Figure 2 3 Note that an ohms math function is only available in the menu if the associated 7751 7752 or 7753 module is installed Figure 2 3 Enabling ohms math function Press SHIFT Press MATH S1IOHMS S1VOHMS S2IOHMS S2VOHMS 7751 7752 7753 7751 7753 7751 7752 7753 7751 7753 in slot 1 in slot 1 in slot 2 in slot 2 Select math function 7753 should be installed in slot 1 for rated accuracy Remote programming As shown in Table 2 2 the CALC FORMat command is used to select an ohms math function Notice that the math setting can be global to all qualified channels or set on a per channel basis by using the lt clist gt parameter NOTE With an ohms math function selected the Model 2790 is actually measuring DCV Therefore if you send SENS1 FUNC to query the selected function it will return VOLT DC Source tracking Model 2790 provides source tracking to ensure that the most recently set source amplitude is used in the selected ohms calculation If the source output level changes the m constant for the calculation will change accordingly Source tracking is enabled automatically when the desired ohms function is selected No other actions are required by the user However if desired source tracking c
59. Test Equipment 99 Washington Street Depot Melrose MA 02176 Phone 781 665 1400 1 800 517 8431 Toll Free 1 800 517 8431 Model 2 90 SourceMeter Switch System y Users Manual A GREATER MEASURE OF CONFIDENCE Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2002 Keithley Instruments Inc All rights reserved Cleveland Ohio U S A Third Printing September 2003 Document Number 2790 900 01 Rev C Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Manual Print History The print history shown below lists the printing dates of all Revisions and Addenda created for this manual The Revision Level letter increases alphabetically as the manual undergoes subsequent updates Addenda which are released between Revisions contain important change information that the user should incorporate immediately into the manual Addenda are numbered sequentially When a new Revision is created all Addenda associated with the previous Revision of the manual are incorporated into the new Revision of the manual Each new Revision includes a revised copy of this print history page Revision A Document Number 2790 900 01 esses enne ener March 2002 Revision B Document Number 2790 900 01 esee March 2002 Revision C Document Number 2790 900 01 0 Septe
60. V amplifier for HIPOT testing It also has a programmable 0 to 50mA constant current I source to measure the resistance of shunt bars and bridgewires Supplementary system components For added versatility or as spares a Model 2790 mainframe 7751 7752 7753 and 7702 modules can be purchased separately However this special order may require a longer delivery time and additional handling charges Test system A typical test system for airbag inflators includes a Model 2790 that is controlled by a PLC or PC and a device handler test station for the inflator The Model 2790 has two slots for switching modules Modules for testing inflators include the Models 7751 7752 and 7753 Model 7702 module can also be used with the Model 2790 NOTE Model 7753 module can be installed in a Model 2790 and it should be installed in slot 1 The 7753 can be installed in slot 2 but measurement accuracy might be adversely affected because cards are always calibrated in slot 1 Figure 1 1 shows a typical test system using a programmable logic controller PLC or a PC When using a PLC communications with Model 2790 are done over the RS 232 interface When using a PC communications with the Model 2790 can be provided using the GPIB or RS 232 Figure 1 1 System connections Device Handler Control Device Handler Mechanical Connection Test Station with Interlock Keithley 2790 7751 7752 ore 7753 Module Inter
61. able preferably 20AWG or larger with a high voltage insulation such as rubber or silicon good for at least 1000V It is the responsibility of the user to use the size and type of cable wire that best suits your needs Keep in mind that Teflon insulated wire performs better in high humidity condi tions but it is not recommended when subjected to mechanical movement like a device handler Recommended cable wire Beldon 8899 cable wire which is stranded I8AWG in size with a thick rubber insulation rated for 5000V working voltage It is very flexible and mechanically durable NOTE The use of an outer protective cable shield is recommended to prevent damage to the wire insulation It should preferably have a foil shield tied to earth ground on one end to provide an extra layer of protection in the event that a wire conductor becomes exposed It will also serve to reduce measurement noise caused by nearby machinery recommended cable shield is available from Zippertubing and covered later in this section Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 4 4 Model 2790 SourceMeter Switch System User s Manual Wiring procedure Use the following procedure to wire 7751 7752 7753 or 7702 module Make sure to add supplementary insulation around the harness for voltages above 42V peak see Figure 4 4 NOTE Figure 4 2 and Figure 4 3 show channel identification for the 7751
62. accuracy might be adversely affected because cards are always calibrated in slot 1 Figure 5 1 System connections DB 9 Cable Device Handler Mechanical Connection 7751 7752 EE Test Station 7753 Module with Interlock RS 232 Cable 9 4 Keithley 7709 5 Test Signal Cabling Keithley 2790 MATH 2 790000 9 DIGITAL Test RS 232 System 5 Expansion IEEE 488 Interlock KPCI 488 GPIB Cable i Interface Cable 7008 3 7008 6 When using a PLC select and configure the RS 232 interface of the 2790 If using a PC select the GPIB interface and set the address of the 2790 Use a cable terminated with a female DB 9 connector to mate to the DIGITAL I O connector of the 2790 Cable must be wired as a straight through cable not null modem cable Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual RS 232 interface PLC or PC A PLC uses the RS 232 interface for communications with the Model 2790 A PC can also use the RS 232 Available 2790 settings for the RS 232 interface e Baud rate 19 2K 9600 4800 2400 1200 600 or 300 e Flow control XonXoff or NONE Txterminator CR LFCR LF or CRLF The RS 232 menu of the 2790 is accessed by pressing and releasing SHIFT and then pressing RS 232 Once in the menu use the
63. all n ROUTe MEMory READ STATe n b ROUTe MEMory CLEar n ROUTe MEMory CLEar ALL Description Create channel pattern for memory n 1 40 Note 7702 channels cannot be included in lt clist gt Assign source values to the channels in lt clist gt that will be output when memory pattern lt n gt is executed Source channels only 127 128 227 or 228 Assign a variable delay to memory pattern lt n gt Time in seconds after closing channels and setting source values before making measurements Immediately execute memory pattern lt n gt If set to ON a reading will be collected after the memory pattern has executed applies to scanning only Clear out memory pattern lt n gt setting all channels to open and removing all digital and analog channels from this memory pattern Clear out all memory patterns You must include at least one measurement channel or a memory pattern that takes a reading ROUT MEM READ STAT x ON Failure to do so results in the scan list being rejected with Error 702 No measurement channel in scanlist Setting up and executing memory patterns To set up memory patterns use the following procedure 1 Program the desired memory pattern locations using the ROUT MEM commands Typically you would set source value s define channels to close and set up delay for each memory location 2 Define DCV 2 wire ohms or 4 wire ohms measure
64. an be disabled or the source that is being tracked can be changed The and SOURCe commands are listed in Table 2 2 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 12 Model 2790 SourceMeter Switch System User s Manual Table 2 2 Commands to select ohms calculations Commands Description Default CALCulate 1 FORMat lt name gt Select math function NONE MXB PERC PERCent RECiprocal S1Iohms S1Vohms S2Iohms S2Vohms CALCulate 1 FOR Mat Query selected math format CALCulate 1 STATe lt b gt Enable or disable math calculation CALCulate 1 STATe Query state of selected math calculation CALCulate 1 DATA LATest Return last result of calculation CALCulate 1 DATA FRESh Return last fresh result of calculation The following commands are set automatically when an ohms math function SxIohms or SxVo hms is selected using the FORMat command No further actions are required by the user CALCulate 1 KMATh MMFactor TRACk b Enable or disable source tracking OFF CALCulate 1 KXMATh MMFactor TRACK Query state of source tracking CALCulate 1 KMATh MMFactor SOURce lt name gt Selects source to be tracked NONE NONE S1ISource S1 VSource 5215 S2VSource CALCulate 1 KXMATh MMFactor SOURce Query source to be tracked 1 Selecting an ohms calculation enables source tracking Selecting any other math function disables
65. ary tests 1 6 programmable logic controller 1 5 voltage source 2 4 Programming errors 2 12 quick disconnect terminal blocks 2 5 Remote programming 2 8 2 11 errors 2 16 opening and closing channels 2 14 3 11 view closed channels 2 15 RS 232 1 5 5 4 Safety warnings 2 6 Screw terminals 4 2 Serial bus RS 232 1 5 5 4 Setting 2 21 shield zipper tube 4 8 short circuit current 2 6 Shunt bar test 1 6 1 7 inflator testing 5 10 Simplified schematic Model 7702 3 4 Models 7751 and 7752 2 3 Slot numbering 2 13 3 9 Source output levels 2 6 outputs and guard terminals 2 5 readback 2 5 tracking 2 11 Specifications A 1 SxIohms 2 9 SxVohms 2 10 System connections 1 5 5 3 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Test circuit shunt bar 5 11 Test configurations 1 4 Test connections shunt bar and bridgewire 5 5 shunt bar HIPOT and bridgewire 5 6 Test System 1 5 Overview 1 1 testing two inflators 1 4 Typical connections Model 7702 3 5 typical test system 1 5 Viewing closed channels Model 7702 3 12 Model 7751 7752 2 15 V source and I V amplifier 2 4 output levels 2 6 readback 1 10 warnings 2 6 Wiring 4 1 Zippertubing 4 8 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com Specifications are su
66. ase of errors for both slots the IL1 message takes precedence Overflowed readings stored in the buffer do not provide interlock status You cannot tell if the overflow readings are true overflows or the result of open interlock see Remote programming errors below Remote programming errors When an open interlock is first detected error 860 slot 1 interlock violation or 861 slot 2 interlock violation occurs The questionable event register in the status byte can be read to determine which interlock tripped see Section 11 of the Model 2790 Reference Manual The firmware polls for interlock violations every 50msec To avoid filling up the error queue once an error is issued for a given interlock it must be reset interlock enabled before another error event will be issued to the status model for the same interlock Error 224 parameter error occurs if you attempt to close channel 18 19 or 21 with interlock open With interlock open channel 20 will close and remain closed while interlock is open ROUT OPEN ALL will open all channels except channel 20 ROUT MULT OPEN will generate error 224 parameter error Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 17 Cable discharge circuit 7751 and 7753 Leakage capacitance exists between signal paths on the switching module and in the test cables This capacitan
67. bject to change without notice All Keithley trademarks and trade names are the property of Keithley Instruments Inc All other trademarks and trade names are the property of their respective companies KENT HLEY Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com
68. ce can be high enough to store a high voltage charge from the V source of the 7751 7753 module As shown in Figure 2 6 capacitance exists between the source terminals Cso and the sense terminals Cap These capacitors can be charged by the V source of the 7751 7753 module during the HIPOT test This unwanted voltage charge could ignite the inflator if it is connected to a bridgewire To prevent a high voltage charge from appearing across the inflator a discharge circuit is used As shown in Figure 2 6 channel 20 is closed to provide discharge paths through 100kQ resistors In general the discharge circuit is controlled as follows When the interlock opens channel 20 closes to discharge the capacitors Channel 20 remains closed as long as interlock remains open see Interlock in Section 5 for details e Opening channel 22 closes channel 20 for approximately 5msec to discharge the capacitors Opening channel 22 selects the I source V source disconnects from rest of module and DUT In general with the test cables connected to the module and the input channels 1 1 and 2 closed the following sequence should be used to properly perform cable discharge 1 Open channel 21 to disconnect the V source and I source from the input 2 Open channel 22 to perform cable discharge NOTE lIfchannel 22 is already open performing the MULT OPEN operation will not close channel 20 to perform cable discharge However the OPEN ALL
69. cess to detect the presence of oxide build up and more accurately measure the resistance of the shunt bar 1 Test the shunt bar using dry circuit ohms channel 24 closed a test current of ImA A resistance gt 100mQ indicates the presence of oxide build up 2 Accurately measure shunt bar resistance without dry circuit channel 24 open and a test current of 50mA or use the 94 function of the Model 2790 Section 6 explains how to use the 94 function of the Model 2790 with the 7702 or 7751 7752 7753 module Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 1 8 Model 2790 SourceMeter Switch System User s Manual Bridgewire test The air bag inflator has two terminals connected to a bridgewire which is coated with a primer that ignites when sufficient current passes through the wire The bridgewire s resis tance is typically from two to three ohms 20 being the most common To avoid unintended ignition the level of test current applied is generally 50mA or less As shown in Figure 1 3 a fixed current is sourced through the bridgewire The voltage across the bridgewire is then measured by the DMM of the Model 2790 Figure 1 3 Bridgewire testing Keithley qo 7751 7752 or 7753 Module Bridgewire Under Test VMEAS DMM RBRID IsOURCE Isour With the low ohms math function selected the reading can be read directly fr
70. channel assignment is formatted as follows SCH where Sis the slot number 1 or 2 CH is the channel number Examples 101 Slot 1 Channel 1 218 Slot 2 Channel 18 NOTE Interlock of the 7751 7752 7753 must be enabled in order to close channel 18 19 or 21 and open channel 20 See Open interlock errors for errors associ ated with open interlock and see Interlock in Section 5 for details on using the interlock Front panel operation As shown in Figure 2 4 the OPEN and CLOSE keys are used to control 7751 7752 and 7753 channels After closing or opening a single channel e A message indicating the action i e 101 CLOSED will be displayed briefly close another channel simply key in the channel number and press ENTER e Press EXIT to exit from the open close menu structure NOTE The edit keys left right up and down arrow keys are used to display a channel number Pressing ENTER opens or closes the channel Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 14 Figure 2 4 Opening closing channels A Opening one or all channels Display ALL option and press OPEN again OPEN ALL Model 2790 SourceMeter Switch System User s Manual OPEN CLOSE Press OPEN key Display MULT option and press ENTER OPEN MULT Display channel number XXX and press ENTER OPEN MULT XXX B Closing a channel Press CLOSE key
71. ck is disabled See General purpose terminal blocks J105 J107 and J108 for additional details General purpose terminal blocks J105 J107 and J108 There are quick disconnect terminal blocks available to the user to provide access to various switching module components These are provided for general purpose test applications that are not necessarily related to airbags J105 matrix backplane and guard The backplane terminals provide access to the relay matrix backplane The matrix backplane is the primary artery for signal routing though the module The guard terminals are typically used for shielding when using the V source and I V con verter for high ohms measurements Guard connections are explained in Section 4 J107 source outputs and guard The I source and V source 7751 7753 are always on and can be accessed by the user at J107 The programmed output is routed to these terminals The guard terminals are typically used for shielding when using the V source and I V converter for high ohms measurements Guard connections are explained in Section 4 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 6 Model 2790 SourceMeter Switch System User s Manual J108 I V converter The user also has access to the input output and ground of the I V converter at J108 Safety warnings WARNING WARNING Integrated safety features protect the 7751 7752 7
72. del 2790 can be used to test inflators With a 7751 7752 7753 module the Model 2790 can safely measure the resistance of bridgewires and shunt bars With a Model 7751 or 7753 module the Model 2790 can use the high voltage method to measure the insulation resistance of an inflator The 7702 module can be used for ohms testing that requires 20 40 channels of 4 wire 2 wire measurements Key features Programmable I source The 7751 7752 and 7753 modules have a built in programmable current source 0 to 50mA This constant current source is used to measure the resistance of bridgewires and shunt bars The Model 2790 has a low ohms math function SxIohms It calculates using the programmed current and measured voltage and displays the resistance in ohms of the bridgewire or shunt bar X is the slot number of the module being used Programmable V source The 7751 and 7753 modules have a built in program mable voltage source 50 to 500V and an I V converter to measure the insulation resistance of an inflator Current through the insulator is applied to the I V con verter where it is converted to a voltage that is measured by the Model 2790 The Model 2790 has a high ohms math function SxVohms It calculates using the programmed V source voltage and measured I V converter output voltage and dis plays the resistance in ohms of the insulation X is the slot number of the module being used Safety features The Model 2790 has built in
73. e switc closed two switches close Channel 24 is a Test assumption Shunt bar connected to Bank 1 1 pole switch see schematic in Figure 2 1 Channels 4 and 5 used for dual inflator where each bridgewire has its own shunt bar See Figure 5 8 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 12 Model 2790 SourceMeter Switch System User s Manual Test procedure Perform the steps in Table 5 1 to test the shunt bar on a single inflator The test current for this measurement cannot exceed 1mA due to the dry circuit hardware limit See Table 5 2 for an example of a test sequence for dual inflator I source readback The 7751 7752 and 7753 modules have source readback capabilities I source readback allows you to verify the test current used for the shunt bar test Details on I source read back are provided in the last topic in this section Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 13 Table 5 1 Test procedure shunt bar Test Step Command Sequence Front Panel Operation 1 Reset 2790 and RST Press SHIFT gt press SETUP gt select open all channels RESTORE FACT 2 Set I source to SOUR CURR 0 001 127 Press SHIFT gt press CARD gt select CONFIG gt select SLOT1 7751 7752 or 7753 gt set I C27 to 01 00 mA gt press ENTER gt pre
74. e 2790 in the one shot trigger mode For front panel operation FACT defaults places the 2790 in the continuous trigger mode This step selects the 2 measurement function of the Model 2790 This step closes the channels to make the connections for the HI contact test This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test This step closes the channels to make the connections for the housing contact test This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 21 Table 5 4 Test procedure contact checks for dual stage inflator Test Step Command Sequence Front Panel Operation 1 Reset 2790 and open all RST Press SHIFT gt press SETUP gt select RESTORE channels FACT 2 Select Q2 SENS FUNC RES Press Q2 3 Close channels to test HI ROUT MULT CLOS Press CLOSE gt select MULTI gt select contact for bridgewire A 8101 114 118 101 gt select 114 gt select 118 gt press EXIT 4 Verify channels that are ROUT MULT CL
75. e calculation VMEAS ISOUR Selecting SIIOHMS sets DMM to DCV IV range This step closes the channels to make the test connections for the bridgewire test It assumes a bridgewire is connected to Bank 1 of a 7751 7752 or 7753 This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test This step closes the channels to make the test connections for the second bridgewire It assumes the bridgewire is connected to Bank 2 of a 7751 7752 or 7753 This step is optional Use it to verify that the correct channels are closed for the test 10 11 For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test I source readback 7751 7752 and 7753 modules have source readback capabilities I source readback allows you to verify the test current used in the bridgewire test Details on I source read back are provided in the last topic in this section Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 17 Insulation resistance HIPOT tests 7751 7753 only WARNING The Models 7751 and 7753 are provided with outputs that are poten tially hazardous if not connected properly It is
76. e con nected to Bank 3 J103 of the 7751 module This guard shielded wire pair should be positioned inside the main cable bundle whose shield is connected to safety earth ground The guard shield should be insulated with an outer jacket A second Zippertubing shield can be used as the guard shield WARNING The guard terminals are connected to the floating ground of the 7751 7752 7753 module Do not connect V source Hi to earth ground If V source Hi is connected to earth ground guard could float up to 500V WARNING not connect V source Hi to earth ground The 7751 7752 7753 mod ule uses a floating ground This floating ground is not connected to safety earth ground Not only will it create a shock hazard by floating up to 500V it will also effectively connect a 1nF capacitor across the V source providing energy storage that could ignite an airbag under fault conditions Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 4 10 Model 2790 SourceMeter Switch System User s Manual NOTE For high ohms measurements gt 1GQ it is recommended that the DUT be con nected between two different banks for example Bank 1 and Bank 3 as seen in test connection figures to reduce the possibility of measurement error caused by leakage resistance Switching module installation Module slot considerations Only one Model 7753 module can be installed in a Model 2790 and it should be instal
77. e of a dual stage inflator 8 9 Close channels to test 2nd bridgwire Verify channels that are closed optional ROUT MULT CLOS 104 105 117 118 121 ROUT MULT CLOS Press CLOSE gt select MULTI gt select 104 gt select 105 gt select 117 gt select 118 gt select 121 gt press EXIT Press SHIFT gt press CARD gt select VIEW gt select SLOTI 7751 7752 or 7753 Press EXIT when finished Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Table 5 2 cont Test procedure bridgewire Test Step Command Sequence Front Panel Operation 10 Perform READ Take reading from display measurement 11 Open all channels ROUT OPEN ALL Press OPEN gt select ALL Test step notes 1 AU ON tA Resetting the 2790 opens all channels selects the DCV function auto range and selects the I source of the 7751 7752 7753 module For remote programming RST places the 2790 in the one shot trigger mode For front panel operation FACT defaults places the 2790 in the continuous trigger mode This step sets the I source to output 50mA which is a typical test current used for this test For front panel operation and a 7751 7753 module the V source output setting will be displayed after setting the I source output This step selects the low resistanc
78. e ohms accuracy and tem perature coefficient data for specific I source and V source output values The following formulas can be used to determine the ohms specification for any valid I source or V source output setting not published in the specification sheet Ohms accuracy and temperature coefficient are specified as percent of reading plus an ohms offset 7751 7752 7753 l source Low ohms specifications using the I source of the 7751 7752 7753 are provided for the following current output settings 50mA 20mA 10 and ImA dry circuit ohms Use the following formulas for other I source settings NOTE The following formulas are only valid when using IVDC range of the Model 2790 DMM When using the SIxOhms math calculation the IV range is selected automatically Ohms accuracy of reading 0 07 T IsourcE Ohms offset 0 03 IsquRCE Q where Isougrce is the current output setting in mA Example Determine ohms accuracy for an I source setting of 30mA of reading 0 07 1 30 0 07 0 03 96 0 10 Ohms offset 0 03 30 Q ImQ Ohms accuracy 30mA 0 10 1m 2 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Specifications A 9 Ohms temperature coefficient TC of reading 0 001 0 025 9 ohms offset 0 001 IsourCE Q C where Isource is the current outp
79. el Note Shown are 7702 channels 1 21 43 and 45 closed to test DUT 1 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 4 Switching Module Wiring and Installation Connections and wiring Provides the details needed to make connections to the screw terminals of the 7751 7752 7753 and 7702 modules Switching module installation Explains how to install 7751 7752 7753 or 7702 in the Model 2790 mainframe Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 4 2 Model 2790 SourceMeter Switch System User s Manual Connections and wiring WARNING WARNING The following information is intended for qualified service personnel Do not make switching module connections unless qualified to do so To prevent electric shock that could result in serious injury or death adhere to following safety precautions Before removing or installing a switching module in the mainframe make sure the mainframe is turned off and disconnected from line power Before making or breaking connections to a switching module make sure power is removed from all external circuitry Do not connect signals that may exceed the maximum specifications of the module Specifications for the switching modules are pro vided in Appendix A Do not apply gt 42V between any terminal HI or LO and chassis ground Do not apply any external sources
80. elrose MA 02176 TestEquipmentDepot com Test circuit for current source readback bridgewire 2790 DMM Keithley 7751 18 7752 or 7753 Bridgewire Under Test IsouRcE Closed channel switch Ch 22 open I source selected Test assumptions To test inflator connected to Bank 1 close channels 1 and 2 To test inflator connected to Bank 2 close channels 4 and 5 NOTE Each channel except channel 24 is a 2 pole switch Therefore when a 2 pole channel is closed two switches close Channel 24 is a 1 pole switch see schematic in Figure 2 1 Open switches not used in the test circuit are not shown Test circuit for current source readback shunt bar 2790 DMM Input LO p Ru V MEAS 10 Keithley 7751 18 7752 7753 Under Test Test assumption Shunt bar connected to Bank 1 Q Closed channel switch Channels 4 and 5 closed for applications with two shunt bars Shunt Bar 5 29 5 30 Model 2790 SourceMeter Switch System User s Manual Memory patterns test As discussed in Section 2 Model 2790 units equipped with firmware revision 04 and higher have the capability of using memory patterns to simplify repetitive test procedures The discussion below shows how to use memory patterns to make contact checks on a dual stage inflator NOTE See Section 2 of the Model 2790 Reference Manual for a more detailed memory patterns example Test circuit As shown in Figure 5 14 there are four con
81. esigner builder s sole responsibility to ensure under all such fault conditions that no hazardous or damaging situations are created Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 3 Card configuration Unlike the 7751 7752 and 7753 modules the 7702 module supports system channel operation That is when an input channel is closed other channels on the module automat ically close to connect the input to the backplane DMM of the Model 2790 Figure 3 1 is a simplified schematic diagram of the Model 7702 module As shown the Model 7702 has channels that are grouped into two banks of twenty channels forty chan nels total Backplane isolation is provided for each bank The first bank contains channels 1 through 20 while the second bank contains channels 21 through 40 Each channel of the 40 channel multiplexer card is wired with separate inputs for HI LO providing fully iso lated inputs The Model 7702 also provides two channels of current input Channels 41 and 42 Although the Model 7702 relays are the latching type relays hold their state even after power has been removed all relay states are set to open a few seconds after either a power cycle or a RST command is issued For a 4 wire function or operation Q4 RTD TEMP Ratio or Channel Average the chan nels are paired as follows e andCH21 CH6 and CH
82. est Safe operation requires the use of a lid interlock Ifa screw is present connect it to safety earth ground using the wire recommended in the user documentation The symbol an instrument indicates that the user should refer to the operating instructions located the manual The A symbol on an instrument shows that it can source or measure 1000 volts or more including the combined effect of normal and common mode voltages Use standard safety precautions to avoid personal contact with these voltages The Al symbol indicates a connection terminal to the equipment frame The WARNING heading in a manual explains dangers that might result in personal injury or death Always read the associated information very carefully before performing the indicated procedure The CAUTION heading in a manual explains hazards that could damage the instrument Such damage may invalidate the war ranty Instrumentation and accessories shall not be connected to humans Before performing any maintenance disconnect the line cord and all test cables To maintain protection from electric shock and fire replacement components in mains circuits including the power transformer test leads and input jacks must be purchased from Keithley Instruments Standard fuses with applicable national safety ap provals may be used if the rating and type are the same Other components that are not safety related may be purchased from other suppliers as long as
83. ewing closed channels eee 2 15 Figure 2 6 Cable discharge circuat 2 18 3 Keithley 7702 Switching Module Figure 3 1 Simplified schematic of Keithley 7702 switching module 3 4 Figure 3 2 Q2 and thermistor TEMP connections 3 5 Figure 3 3 Q4 and RTD TEMP connections eee 3 6 Figure 3 4 Current connections DCI and ACI 3 6 Figure 3 5 Voltage connections or ACV 3 7 Figure 3 6 andkeys 4e cocci tt E SE PR rere 3 10 Figure 3 7 CLOSE 3 10 Figure 3 8 4 2 eint ei te pp P PAP REPERTA 3 11 Figure 3 9 Viewing closed channels see 3 12 Figure 3 10 Using 7751 7753 V source with 7702 module dual multiplexer ecrire soos 3 14 4 Switching Module Wiring and Installation Figure 4 1 Screw terminal ACCESS cte E R 4 3 Figure 4 2 Model 7751 7752 7753 screw terminal channel designations 4 5 Figure 4 3 Model 7702 screw terminal channel designations 4 6 Figure 4 4 Wire dressing 7751 7752 7753 einek 4 7 Figure 4 5 Zippertubing shield ZTZ SH3 series 4 8 Figure 4 6 Installed Zippertubing shield 2 222 2 4 9 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com
84. f measurement error caused by leakage resistance Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 9 Interlock connections Figure 5 6 When using a test fixture or safety shield that has an interlock switch con nect interlock as shown in Figure 5 6 Figure 5 6 Interlock connections Keithley 7751 7752 or 7753 J106 Test Station INTERLOCK 45V Connect to safety earth ground using 418 AWG wire or larger INTERLOCK Lid shield open switch open Sources disconnected Lid shield closed 2 switch closed 2 Sources connected WARNING DO NOT permanently short out the interlock Interlock is an essential safeguard to prevent personal injury due to electric shock and or accidental ignition of an inflator It is a good safe practice to use an interlock test station that always disables the sources and provides protection from inflator ignition Interlock NOTE enabled interlock allows the I source and V source 7751 7753 to be con nected to the rest of the switch matrix An open disabled interlock does not dis able the sources The sources are always on and available at the J107 terminals of the module Interlock has no effect on the source outputs at J107 The selected source can also be accessed at J105 Source Hi and Source Lo when interlock is enabled With interlock open the sources are di
85. fied test circuit for using the 22 function of the Model 2790 with the 7751 7752 7753 module to measure high ohms DUT 1 insulation resistance up to 120MQ The DUT is connected to channels 10 and 11 Bank 4 of the 7751 7752 7753 To connect the DUT to the DMM of the Model 2790 channels 10 11 13 and 18 must be closed Note that the voltage across the DUT is sensed through the fuse resistance so that measurement accuracy can be affected by fuses when making low ohms measurements NOTE When using the 2 wire ohms function of the Model 2790 to measure a resistance through one of the 775X modules there will be an offset in the measured value due the signal path resistance of the 775X module see Fuse resistance consid erations on page 6 2 This path resistance is due to safety circuitry fuses in the module The offset can be corrected for by measuring a zero ohm load short circuit and then using the REL function see Section 5 of the Model 2790 Refer ence Manual to remove the offset 4 wire ohms measurements are not affected by the safety circuitry Figure 6 6 Using Model 2790 2 wire ohms with 7751 7752 7753 module high ohms measurements Keithley 2790 222222222222 Fuse Keithley 7751 7752 7753 1 Resistance Input 13 108 Source Ch 10 DMM lt 120MQ Source Ch 11 LO Channel closed by user multiple channel operation Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 Te
86. fier 200kQ For the 7753 20 000 x is the m factor for the calculation m X b 20 000 is the value of the feedback resistor Rp for the I V amplifier Rp 20k 2 Vmeas 15 the output voltage of amplifier measured by the DMM of the Model 2790 It is the X variable for the calculation m X b When the Sx Vohms calculation is selected the Model 2790 measures voltage X and calculates m X b using the above factors The displayed reading will be in ohms Q This selection also sets DMM to DCV 10V range Note that the VygAg reading will be negative Because the output of the V I amplifier is inverted the negative value of m will cause the ohms reading to be displayed as a positive value When using the high ohms calculation SxVohms the highest DCV measurement range that can be selected is 10V Attempting to select a higher range will cause error 222 Parameter out of range If V 10mV an overflow will occur If V 12V an underflow will occur Attempting to turn Autoranging on generates error 221 Settings conflict over the GPIB or a NO AUTORANGE message on the display if done from the front panel AUTO key NOTE Readings for both the 7751 and 7753 modules will overflow when the I V output is greater than 9mV and underflow when the I V output is less than 12V Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790
87. following key press sequence to select and configure the RS 232 Select RS 232 ON select BAUD rate select FLOW control select Tx TERMinator GPIB PC only The GPIB which is faster than RS 232 can be used if an IEEE 488 Interface card e g KPCI 488 is installed in the computer The GPIB menu of the Model 2790 is accessed by pressing and releasing SHIFT and then pressing GPIB Once in the menu use the following key press sequence Select GPIB ON select ADDRess address 16 is set at factory Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 5 Test signal connections There are four main test connection drawings Figures 5 2 5 3 5 4 and 5 5 but you only need to use the one that applies to your test system Select the drawing that best suits your needs and disregard the other three NOTE All the test circuits and procedures in this section assume that the inflator is con nected to the 7751 7752 7753 module as shown in Figure 5 2 through Figure 5 5 Single stage inflator test connections Figure 5 2 Use this connection scheme if using a Keithley 7752 module It can also be used for the 7751 or 7753 module if not performing the HIPOT test Figure 5 3 Use this connection scheme if using a Keithley 7751 or 7753 mod ule It includes the connections for the HIPOT test Figure 5 2 Test connecti
88. hecks for dual stage inflator 5 21 Table 5 5 Test procedure V source readback 5 23 Table 5 6 Test procedure HIPOT 22 202022 1250 0 5 26 Table 5 7 Command sequence for memory patterns test example USING 5 5 31 Table 5 8 Command sequence for memory patterns test example using individual memory pattern recall 5 33 6 Model 2790 DMM Ohms Functions Table 6 1 Commands to set offset compensated ohms 6 5 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Test System Overview Introduction Summarizes the switching modules that are used with the Model 2790 to test inflators Covers some key features of the Model 2790 and defines explains technical terms associated with airbag inflators Model 2790 configurations Explains the various mainframe module combina tions available from Keithley Test system Shows a typical test system used to test inflators Inflator tests Explains the three basic tests for inflators shunt bar bridgewire and insulation resistance HIPOT Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Introduction Model 2790 SourceMeter Switch System User s Manual When used with one or two switching modules the Mo
89. ire ohms Range 100 Integration period 1 PLC After setting up memory locations Table 5 7 the scan is enabled triggered and readings are stored in the buffer for recall once the scan is complete For the memory pattern loca tion recall shown in Table 5 8 memory locations are first set up and each location is recalled in succession Table 5 7 Command sequence for memory patterns test example using scanning RST ROUT Command Sequence MEM CLE ALL Set up memory location 1 ROUT ROUT ROUT SENS SENS SENS MEM CHAN 1 101 114 118 MEM DEL 1 0 MEM READ STAT 1 ON FUNC RES M1 RES RANG 100 M1 RES NPLC 1 M1 Set up memory location 2 ROUT ROUT ROUT SENS SENS SENS MEM CHAN 2 104 114 118 MEM DEL 2 0 MEM READ STAT 2 ON FUNC RES M2 RES RANG 100 M2 RES NPLC 1 M2 Description Restore GPIB defaults Clear all memory pattern locations Set channels 1 14 and 18 for memory location 1 Set delay to 0 Enable reading Select 2 wire ohms Select 1000 range Select 1 PLC Set channels 4 14 and 18 for memory location 2 Set delay to 0 Enable reading Select 2 wire ohms Select 1000 range Select 1 PLC Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 32 Model 2790 SourceMeter Switch System User s Manual Table 5 7 cont Command sequence for memory patterns test e
90. led in slot 1 A 7753 module can be used in slot 2 but measurement accuracy might be adversely affected because cards are always calibrated in slot 1 Power supply restrictions with the 7753 module Under some conditions low line maximum current draw two 7753 modules could draw enough power to cause the Model 2790 to reset To avoid this situation installed modules are checked at power up If a 7753 module is present the other slot must be empty or pop ulated with a 7702 module If this condition is violated a Model 7753 plus any other 775x module the Model 2790 will lock up with the message 1 7753 ONLY displayed and all annunciators will turn on In this case you must remove one module and cycle power to continue Installation procedure A Keithley switching module simply slides into one of two slots in the rear panel of the Model 2790 1 Turn off the Model 2790 and make sure there is no external power connected to it or the module External sources should never be used anywhere in the test system to take advantage of the 2790 improvements that reduce the risk of airbag detonation If a slot cover is installed remove it and retain for future use 3 With top cover side up slide the connector end of the module into the mainframe Make sure the front edge of the card is in the track for the slot 4 Push the module all the way in until it mates with the backplane connector of the mainframe 5 Hand tighten the two scre
91. lock Inflator Under Test Test Signal Slot 1 Cabling MATH 2 790000 9 Slot 2 DIGITAL Test RS 232 System Expansion IEEE 488 Interlock F KPCI 288 i Interface 1 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 1 6 Model 2790 SourceMeter Switch System User s Manual Inflator tests There are three primary tests for an inflator Shunt bar test Bridgewire test e Insulation resistance HIPOT test NOTE Interlock The three primary tests can only be performed if the interlock of the 7751 7752 7755 module is enabled With interlock open disabled the I source of the 7751 7752 7753 module and the V source of the 7751 7753 module are disconnected from the switching module matrix Details on the interlock are pro vided in Section 5 The following information provides an overview of the three tests that are used to test an inflator The actual detailed procedures for these tests are provided in Section 5 Shunt bar test NOTE shunt bar test is typically tested again after all other inflator tests are completed As a final test it verifies that it is safe to install the inflator in a vehicle A shunt bar shorting clip is used to short the bridgewire s to prevent accidental ignition when handling or installing the inflator However an oxide can form between the shunt and the inflator terminals It is this high
92. losed SLOT2 7751 or 7753 Press EXIT when finished optional 6 Perform READ Take reading from display measurement 7 Perform cable ROUT OPEN ALL Press OPEN gt select ALL discharge and open all channels The following steps are used to test insulation resistance for the second bridgewire of a dual stage inflator 8 Close channels to ROUT MULT CLOS Press CLOSE gt select MULTI gt select 104 gt select perform HIPOT 104 106 108 116 118 121 106 gt select 108 gt select 116 gt select 118 gt select test for second 122 223 121 gt select 122 gt select 123 gt press EXIT bridgewire Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 27 Table 5 6 cont Test procedure HIPOT 9 10 11 Test Step Command Sequence Front Panel Operation Verify channels ROUT MULT CLOS Press SHIFT gt press CARD gt select VIEW gt select that are closed SLOT1 7751 or 7753 Press EXIT when finished optional Perform READ Take reading from display measurement Perform cable ROUT OPEN ALL Press OPEN gt select ALL discharge and open all channels Test step notes 1 AU 1 ON tA 11 Resetting the 2790 opens all channels selects the DCV function auto range and selects the I source of the 7751 7753 module For remote programming RST places the
93. losed using system channel operation the DUT con nects to the DMM of the Model 2790 Figure 6 3 Using Model 2790 4 wire ohms with 7702 module low ohms measurements oe eee tee SLES Ee i Keithley 7702 Input Channel closed by user system channel operation The channels that also close when Ch 1 is closed are not shown These include the paired input channel Ch 21 the 4 pole relay Ch 43 and backplane channels Chs 44 and 45 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 6 7 Figure 6 4 shows the simplified test circuit for using the 92 function of the Model 2790 with the 7702 module to measure high ohm DUT 1 insulation resistance up to 120MQ The DUT is connected to channel 1 of the 7702 When channel 1 is closed using system channel operation the DUT connects to the DMM of the Model 2790 Figure 6 4 Using Model 2790 2 wire ohms with 7702 module high ohms measurements Keithley 2790 Keithley 7702 Input lt 120MQ Input LO Channel closed by user system channel operation Not shown is the backplane channel Ch 45 that also closes when channel 1 is closed Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 6 8 Model 2790 SourceMeter Switch System User
94. losing input channel 4 connects the second bridgewire Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 25 Figure 5 12 Test circuit HIPOT Keithley 7751 7753 Inflator i P Inflator i Housing 3 and 6 Shunt Internal m Bar VsOuR Rr shunts VMEAS 10 Faros 20V y 200ko 7751 Under VMEAS 216 w Test 2 7753 VMEAS Selects V source 200kQ 7751 20kQ 7753 Input HI IN Amplifier 7751 7753 2790 DMM Input LO 69 Closed channel switch Test assumptions To test a single inflator connected to Bank 1 close channels 1 and 3 Closing channel 3 connects an internal built in shunt across the bridgewire To test a dual inflator connected to Banks 1 and 2 close channels 3 4 and 6 Closing channels 3 and 6 connects internal built in shunts across the two bridgewires NOTE Each channel except channel 23 is a 2 pole switch Therefore when a 2 pole channel is closed two switches close Channel 23 is a 1 pole switch see schematic in Figure 2 1 Open switches not used in the test circuit are not shown Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 26 Model 2790 SourceMeter Switch System User s Manual Test procedure HIPOT WARNING The following test procedure
95. mber 2003 Keithley product names are trademarks or registered trademarks of Keithley Instruments Inc Other brand names are trademarks or registered trademarks of their respective holders Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Safety Precautions The following safety precautions should be observed before using this product and any associated instrumentation Although some instruments and accessories would normally be used with non hazardous voltages there are situations where hazardous conditions may be present This product is intended for use by qualified personnel who recognize shock hazards and are familiar with the safety precautions required to avoid possible injury Read and follow all installation operation and maintenance information carefully before using the product Refer to the manual for complete product specifications If the product is used in a manner not specified the protection provided by the product may be impaired The types of product users are Responsible body is the individual or group responsible for the use and maintenance of equipment for ensuring that the equip ment is operated within its specifications and operating limits and for ensuring that operators are adequately trained Operators use the product for its intended function They must be trained in electrical safety procedures and proper use of the instrument They must be
96. ment function s for each memory pattern location Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 22 Model 2790 SourceMeter Switch System User s Manual 3 Once a location is defined use the ROUT MEM REC command to recall a mem ory pattern location then trigger and acquire a reading using READ 4 After taking the measurement use ROUT OPEN ALL to open all channels An example that sets up and executes memory location 1 is shown in Table 2 5 See Memory patterns test on page 5 30 for a more detailed example Table 2 5 Basic memory pattern example Command Description ROUT MEM CHAN 1 0108 115 118 Specify relays to close ROUT MEM DEL 1 0 Set memory delay 0 SENS FUNC RES M1 Select 2 wire ohms measurement function SENS RES RANG 100 M1 Select 1000 fixed measurement range SSENS RES NPLC 1 M1 Set A D integration time to 1 power line cycle ROUT MEM REC 1 Recall Memory Location 1 READ Initiate a measurement and request the result ROUT OPEN ALL Open all relays Memory pattern command options CALCulate SENSe and UNIT subsystem commands with a lt clist gt channel list parameter associated with Model 2790 DC volts 2 wire ohms and 4 wire ohms measure ment functions can include a memory pattern lt clist gt parameter Mn that allows you to assign those functions to specific memory pattern locations For example
97. ming the HIPOT test Figure 5 5 Use this connection scheme if using a Keithley 7751 or 7753 mod ule It includes the connections for the HIPOT test Figure 5 4 Test connections shunt bar and bridgewire bar testing dual stage inflator Dual Stage Inflator A Shunt Bar Testing B Bridgewire Testing Remo mim mim mim im mmm mmm mmm ee ees Keithley 7751 7752 or 7753 i Bank 1 J101 SRC HI SEN HI i SRC LO SEN LO SRC HI SENHI SRC LO NOTE Some wires are shown in bold to make it easier to follow the i SEN LO signal paths Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 8 Model 2790 SourceMeter Switch System User s Manual Figure 5 5 Test connections shunt bar HIPOT and bridgewire testing dual stage inflator Dual Stage Inflator A Shunt Bar and B Bridgewire Testing HIPOT Testing Keithley 7751 7753 Bank 1 J101 SRC HI SEN HI SRC LO SEN LO Built in shunt Available for use during HIPOT testing Channels 3 and 6 are closed for HIPOT and open for shunt bar and bridgewire tests SRC HI SEN HI SRCLO NOTE Some wires are shown in bold to make it easier to follow the signal paths SEN LO NOTE For high ohms measurements gt 1GQ it is recommended that the DUT be connected between two different banks for example Bank 1 and Bank 3 as seen in test connection figures to reduce the possibility o
98. multiple channel operation must be used to control channels for this application All channels of the 7751 7753 module are to remain open NOTE Section 2 Setting source output levels explains how to set the output of the V source of the 7751 7753 module During the testing process channels 43 and 45 of the 7702 are to remain closed To test DUT 1 input channels 1 and 21 are then closed To test DUT 2 input channels 2 and 22 are closed DUT 3 through 20 are tested in a similar manner by closing the appropriate pair of input channels Keep in mind that when testing a DUT only the two appropriate inputs are closed other input channels must be open NOTE See Multiple channel operation Dual independent multiplexers in Section 2 of the Model 2790 Reference Manual for details on using the 7702 module as a dual multiplexer In Figure 2 9 of the reference manual the 7751 7753 V source would replace the External Source Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 3 10 Using 7751 7753 V source with 7702 module dual multiplexer Keithley 7751 7753 Module Vsrc HI All 7751 7753 channels open VSOURCE i 1 DMM i D Input i LO 4 1 i 1 1 i 1 1 i 1 1 i 1 1 i Q Closed channel E a O Open chann
99. nals 2 6 Inflator tests 1 6 Installation 4 1 4 10 installation 4 10 Insulation resistance 1 2 Model 7751 5 17 Insulation resistance HIPOT test 1 9 Interlock 1 6 2 5 interlock errors 2 16 Invalid current error 2 12 I source output levels 2 6 readback 1 8 leakage resistance 1 9 Low ohms calculation 2 9 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Manual cable discharge 2 18 Math 2 9 matrix backplane and guard terminals 2 5 Memory 2 21 2 22 2 23 5 30 memory 2 20 Memory patterns setting up 2 21 Model 7700 7702 and 7703 Introduction 1 Model 7702 3 1 22 Wire and Thermistor connections 3 5 24 Wire and RTD connections 3 6 Channel assignments 3 9 Connection Log 3 7 Current connections AC or DC 3 6 opening and closing channels 3 9 screw terminal channel designations 4 6 Typical connections 3 5 Viewing closed channels 3 12 Voltage connections DC or AC 3 7 Wiring procedure 4 4 Model 7751 7752 2 1 interlock 2 16 manual cable discharge 2 18 Screw terminal channel designations 4 5 Viewing closed channels 2 15 Wire dressing 4 7 Wiring procedure 4 4 Module 4 10 Multiple channels Control commands 2 8 2 12 2 14 3 11 6 5 operation 2 13 ohms math function 2 11 OPEN key 3 10 3 11 Opening and closing channels Model 7702 3 9 Model 7751 7752 2 13 operation multiple channel 2 13 Overview 1 1 oxide build up 1 7 PLC 1 5 Power 4 10 prim
100. ne 7751 and one 7752 module This test system includes a 7751 module and a 7752 module The high voltage module 7751 can be used for HIPOT testing while the I source of the second module 7752 can be used to test other non inflator type circuitry i e pushbutton switches and resistors on the steering wheel The I source allows accurate resistance measurements up to 100Q 2790 L configuration one 7752 module This test system includes a single 7752 module It is applicable for testing that does not require high voltage HIPOT testing but still needs the programmable I source for low ohms testing Insulation resistance up to 120M can be measured using the 22 function of the Model 2790 2790 H L A 7702 configuration one 7751 7752 7753 one 7702 module This test system includes a 7751 7752 or 7753 module and a 7702 module The 7702 module can be used for non inflator related ohms testing that requires 20 40 channels of 4 wire 2 wire measurements Typical tests using the 7702 module include burn in life QA testing of multi pin connectors wiring harnesses power distribution fuse centers switches and relays and backplanes Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 1 5 2790 A configuration one 7753 module This test system includes a single 7753 module This module has a programmable 50 to 500 V source and I
101. nnected to the internal DMM Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 5 Typical connections The following examples show typical 7702 wiring connections for the following types of measurements Q2 and thermistor temperature connections see Figure 3 2 Q4 and RTD temperature connections see Figure 3 3 Current connections DCI or ACT see Figure 3 4 Voltage connections or see Figure 3 5 Figure 3 2 22 and thermistor TEMP connections Channel 1 LO Resistors or Thermistors HI Channel 40 Channels 2 39 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 3 6 Model 2790 SourceMeter Switch System User s Manual Figure 3 3 24 and RTD TEMP connections Resistor or cheney 4 Wire RTD LO Channels 2 19 e e e HI h 12 Resistor or 4 Wire RTD LO HI Channel 21 LO Channels 22 39 e HI Channel 40 NOTE For details on using the 7702 module to make ohms measurements see Section 6 Model 2790 DMM Ohms Functions Figure 3 4 Current connections DCI and ACI Channel 41 HI Channel 42 LO Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 7 Figure 3 5
102. nt panel operation FACT defaults places the 2790 in the continuous trigger mode This step selects the 92 measurement function of the Model 2790 This step closes the channels to make the connections for the HI contact test bridgewire A This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test This step closes the channels to make the connections for the HI contact test bridgewire B This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test This step closes the channels to make the connections for the housing contact test This step is optional Use it to verify that the correct channels are closed for the test For remote programming READ triggers and requests a single reading Always open all channels at the beginning and end of a test Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 22 Model 2790 SourceMeter Switch System User s Manual V source readback Test circuit The V source readback circuit is shown in Figure 5 11 Closing channels 13 18 21 22 and 23 routes the voltage to the DMM of the Model 2790 The DMM needs to be
103. nterlock errors are provided in Section 2 see Open interlock errors The following explains the more common errors associated with open interlock Front panel messages e INTRLCK OPEN is displayed briefly if you attempt to close channel 18 19 or 21 with interlock open With the INPUTS switch in the REAR position in readings will overflow OFLO when the interlock is open The IL1 or IL2 message will also be displayed to identify which slot is in violation With both slots in violation IL1 message takes precedence Remote programming errors When an open interlock is first detected error 860 slot 1 interlock violation or 861 slot 2 interlock violation occurs With interlock open error 224 parameter error occurs if you attempt to close chan nel 18 19 or 21 It also occurs if you use ROUT MULT OPEN to open channel 20 while interlock is open Shunt bar test The resistance of the shunt bar is typically 10 to 1009 It is possible for the contact sur faces of a shunt bar to oxidize even in normal operating conditions The presence of any such oxides affects the resistance of the shunt bar It may be desirable to test the shunt under dry circuit conditions to prevent the breakdown of any oxide layers which could give a false indication of the shunt resistance Dry circuit conditions require that the voltage applied to the DUT be limited to 20mV or less Closing channel 24 of the 7751 7752 7753 module enables
104. ocedure Single stage inflator Perform Test Steps 1 through 7 in Table 5 2 Dual stage inflator Perform Test Steps 1 through 11 in Table 5 2 WARNING To prevent accidental ignition of the inflator ALWAYS open all chan nels in the test system at the beginning and end of each test Table 5 2 Test procedure bridgewire 1 2 3 4 5 6 7 Test Step Reset 2790 and open all channels Set I source to 50mA Select and enable the low ohms calculation Close channels to test bridgewire Verify channels that are closed optional Perform measurement Open all channels Command Sequence RST SOUR CURR 0 05 127 CALC1 FORM S1I CALC1 STAT ON ROUT MULT CLOS 8101 102 117 118 121 ROUT MULT CLOS READ ROUT OPEN ALL Front Panel Operation Press SHIFT gt press SETUP gt select RESTORE FACT Press SHIFT gt press CARD gt select CONFIG gt select SLOT1 7751 7752 or 7753 gt set I C27 to 50 00 mA gt press ENTER gt press EXIT or ENTER Press SHIFT gt press MATH gt select SIIOHMS Press CLOSE gt select MULTI gt select 101 gt select 102 gt select 117 gt select 118 gt select 121 gt press EXIT Press SHIFT gt press CARD gt select VIEW gt select SLOTI 7751 7752 or 7753 Press EXIT when finished Take reading from display Press OPEN gt select ALL The following steps are used to test the second bridgewir
105. oefficient 100V 0 53 2000 C Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 12 Specifications Model 2790 SourceMeter Switch System User s Manual Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com airbag inflators 1 2 Bridgewire test 1 8 bus programming 2 8 2 11 Cable discharge 2 4 circuit 2 17 2 18 Cabling requirements 4 3 Card configuration Model 7702 3 3 Models 7751 and 7752 2 2 G Channel assignments Model 7702 3 9 Channels closing Model 7702 3 9 Model 7751 7752 2 13 Numbering 2 13 3 9 3 10 5 2 Command Sequence bridgewire 5 15 contact checks 5 20 5 21 5 31 5 33 HIPOT 5 26 shunt bar 5 13 V source readback 5 23 Commands Multiple channel control 2 8 2 12 2 14 3 11 6 5 Connection log Model 7702 3 8 Model 7751 7752 2 19 Connections and wiring 4 2 Contact checks 1 10 discharge circuit 2 17 dual inflator 1 4 L Errors 241 870 2 12 Front Panel 3 10 Open interlock errors 5 10 operation 2 11 message 2 16 opening and closing channels 2 13 view closed channels 2 15 remote programming test procedures 5 2 test procedure bridgewire 5 15 contact checks 5 33 HIPOT 5 26 shunt bar 5 13 V source readback 5 23 Fuse 6 2 5 20 5 21 5 31 GPIB 1 5 5 4 Guarding 4 9 Hardware missing 2 12 High ohms calculation 2 10 math function 1 10 I V converter termi
106. om the display of the Model 2790 I source readback Before performing the bridgewire test you can verify the actual current flowing in the test circuit by using the I source readback circuit NOTE accurate ohms reading can be achieved using the 94 function of the Model 2790 1mA fixed See Section 6 for details Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 1 9 Insulation resistance HIPOT test 7751 and 7753 only WARNING The Models 7751 and 7753 are provided with outputs that are poten tially hazardous if not connected properly It is the responsibility of the customer to operate instruments in a safe manner Be sure to read and follow all installation and operating instructions before attempting to use the 7751 7753 HIPOT function The leakage resistance between each of the initiators and the housing must be verified As shown in Figure 1 4 this is performed by applying a voltage typically 500 between the bridgewire and the housing The resultant test circuit current is applied to an I V amplifier where it is converted to a voltage This voltage is then measured by the DMM of the Model 2790 NOTE lIfnot using a 7751 7753 module in your test system resistance up to 120MQ can be measured using the 2 function of the Model 2790 Figure 1 4 HIPOT testing 7751 7753 RHIPOT
107. on the 1000V range to measure the maximum output of the 7751 7753 500 Figure 5 11 V source readback circuit Input Hi Selects PS 2790 DMM Input Lo Amplifier i i i i 1 VSOURCE e i V i i Closed channel switch NOTE Each channel except channel 23 is a 2 pole switch Therefore when a 2 pole channel is closed two switches close Channel 23 is a 1 pole switch see schematic in Figure 2 1 Open switches not used in the test circuit are not shown Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Test procedure 5 23 Perform the steps in Table 5 5 to verify the open circuit output of the V source Table 5 5 Test procedure V source readback Test Step Command Sequence Front Panel Operation 1 Reset 2790 and RST open all channels 2 Close channels to ROUT MULT CLOS 113 118 121 connect V source 122 123 3 Verify channels ROUT MULT CLOS that are closed optional 4 Perform READ measurement 5 Open all channels ROUT OPEN ALL Press SHIFT gt press SETUP gt select RESTORE FACT Press CLOSE gt select MULTI gt select 113 gt select 118 gt select 121 gt select 122 gt select 123 gt press EXIT Press SHIFT gt press CARD gt select VIEW gt select SLOT1 7751 or 7753 Press EXIT when finished Take
108. ons shunt bar and bridgewire testing single stage inflator cup Single Stage Inflator Keithley 7751 7752 0 7753 1 A Shunt Bar Testing Bridgewire Testing Bank 1 SRCHI Shunt i SEN HI Bar SRCIO SENLO Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 5 3 Test connections shunt bar HIPOT and bridgewire testing single stage inflator Single Stage Inflator A Shunt Bar and B Bridgewire Testing HIPOT Testing Keithley 7751 7753 Bank 1 J101 Built in shunt Available for use during HIPOT testing Channel 3 closed for HIPOT and open for shunt bar and bridgewire tests NOTE Some wires are shown in bold to make it easier to follow the signal paths NOTE For high ohms measurements gt 1GQ it is recommended that the DUT be connected between two different banks for example Bank 1 and Bank 3 as seen in test connection figures to reduce the possibility of measurement error caused by leakage resistance Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 7 Dual stage inflator test connections Figure 5 4 Use this connection scheme if using a Keithley 7752 module It can also be used for the 7751 or 7753 module if not perfor
109. opera tion will perform cable discharge When the OPEN ALL operation is performed the following sequence of actions 1 Opens channel 21 to disconnect all sources 2 Opens channel 22 3 Closes channel 20 for 5 to perform cable discharge 4 Opens all channels NOTE Section 5 the test procedure for HIPOT uses the OPEN ALL operation to perform cable discharge see steps 7 and 11 in Table 5 6 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Manual cable discharge The discharge circuit can also be activated manually at any time by closing channel 20 of the 7751 7753 module Typically manual discharge is used when a discharge time 5msec is desired Figure 2 6 Cable discharge circuit Keithley 7751 7753 Source Q Closed channel switches Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Connection log Make a copy of Table 2 4 and affix it to the cover of the 7751 7752 7753 module Use it to record connection information and channel descriptions as needed 2 19 Table 2 4 Connection log Model 7751 7752 7753 Bank Channel Color Description Source Sense Bank 2 L
110. osed Examples ROUT OPEN ALL Open all channels ROUT CLOS 8101 Close 7702 channel 1 in slot 1 ROUT CLOS Return closed channel Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 3 12 Model 2790 SourceMeter Switch System User s Manual Viewing closed channels Closed channels can be viewed from the VIEW item of the CARD menu Closed channels including backplane channels and 2 pole 4 pole relay are scrolled across the display of the Model 2790 The menu structure is accessed by pressing and releasing SHIFT and then pressing CARD As shown in Figure 3 9 the closed channels will scroll across the display four dots identify the end of the channel string e Use the ENTER key to pause and resume scrolling e Press EXIT to return to the normal display state NOTE For remote programming all closed channels can be identified using ROUT MULT CLOS and ROUT MULT CLOS STAT lt clist gt See Table 2 2 in the Model 2790 Reference Manual Figure 3 9 Viewing closed channels Press Press Select SLOTx 7702 SLOTx Slot1 or Slot2 101 145 Select module Shows channels 101 and 145 closed Closed channels scrolled Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 3 13 Using 7751 7753 V source with 7702 module WAR
111. p p at 50Hz or 60Hz INPUT PROTECTION Front 1000V Rear 300V 7702 card only Resistance MAX 4WO LEAD RESISTANCE 10 of range per lead for 100Q and 1kQ ranges 1kQ per lead for all other ranges OFFSET COMPENSATION Selectable on 4WQ 1000 1kQ and 10kQ ranges CONTINUITY THRESHOLD Adjustable 1 to 1000 Q INPUT PROTECTION Front 1000V Source Inputs 350V Sense Inputs Rear 300V 7702 card only DC Current Shunt Resistors 100mA 3A 0 1Q 20mA 5Q Input Protection 3A 250V fuse DC Notes 20 overrange except on 1000V and 3A 2 Add the following to ppm of range uncertainty 100mV 15 100 2ppm 1000 30ppm lt 1 2ppm 10mA and 1A 10 100mA 40ppm 2 measured with 10MQ input resistance DMM gt 10GQ DMM on 10MQ and 100MQ ranges Relative to calibration accuracy 5 For signal levels gt 500V add 0 02ppm V uncertainty for portion exceeding 500V 6 Specifications are for 4 wire 100Q with offset compensation on With offset compensation on OPEN CKT VOLTAGE is 12 8V For 2 wire Q add 1Q additional uncertainty 7 Must have 10 matching of lead resistance in Input HI and LO Test current 0 7pA LOMQ Add the following to ppm of reading uncertainty when using plug in modules 10kO 100kQ 1MQ 10MO 100 220 ppm 2200 ppm 7702 7751 7752 Add 1V when used with plug in modules 1 For RATIO DCV only For AVERAGE DCV only Available
112. protected from electric shock and contact with hazardous live circuits Maintenance personnel perform routine procedures on the product to keep it operating properly for example setting the line voltage or replacing consumable materials Maintenance procedures are described in the manual The procedures explicitly state if the operator may perform them Otherwise they should be performed only by service personnel Service personnel are trained to work on live circuits and perform safe installations and repairs of products Only properly trained service personnel may perform installation and service procedures Keithley products are designed for use with electrical signals that are rated Measurement Category I and Measurement Category II as described in the International Electrotechnical Commission IEC Standard IEC 60664 Most measurement control and data I O signals are Measurement Category I and must not be directly connected to mains voltage or to voltage sources with high transient over voltages Measurement Category II connections require protection for high transient over voltages often as sociated with local AC mains connections Assume all measurement control and data I O connections are for connection to Category I sources unless otherwise marked or described in the Manual Exercise extreme caution when a shock hazard is present Lethal voltage may be present on cable connector jacks or test fixtures The American National Standards In
113. re 4 6 Figure 4 5 Zippertubing shield ZTZ SH3 series Zipper NOTE Drawing proportions are not scaled to actual length of the shield and ground wire Foil Wrapper gt To Inflator Test Signal Wires To Switching Module Ground Wire Connect to oat safety earth ground Assembled Cable Bundle Test Equipment Depot 800 517 8431 99 Washington Street Melrose 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 4 9 Figure 4 6 Installed Zippertubing shield Test Station Ground wrap cable bund Safety Earth Keithley 7751 7752 Ground 7753 or 7702 Guarding NOTE The typical high ohms measurement applications for the 7751 7753 V source does not require guarding Guarding only needs to be used for the most demand ing noisy situations or when measuring gt 1GQ which is the maximum resis tance specified for the 7751 7753 A second inner shield can be used for high ohms measurements that use the 7751 7753 V source and I V converter This guarded shield may reduce noise and cable leakage that could result in measurement errors The guard terminals are available at J105 and J107 Guard is connected to a shield that surrounds the Source Lo and Sense Lo test leads that connect to the housing of the inflator In Figure 5 3 Section 5 use the guard shield to surround the two wires that ar
114. repetitive tests Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 2 Model 2790 SourceMeter Switch System User s Manual Introduction There are three primary tests for an inflator Shunt bar test e Bridgewire test e Insulation resistance HIPOT test This section focuses on performing the inflator tests Details on the tests are provided in Section 1 WARNING Since the Model 2790 system is not an intrinsically safe device it is the responsibility of the user to ensure that external protection be provided either by an inherently safe electrical barrier and or a safety barrier around the DUT or airbag to prevent injury in case of detonation Test procedures Tables Test procedures for remote programming and front panel are presented in tables All test procedures assume the 7751 7752 or 7753 module is installed in slot 1 of the mainframe NOTE Only one Model 7753 can be installed in a Model 2790 and it should be installed in slot 1 A 7753 module can be used in slot 2 but measurement accuracy might be adversely affected because cards are always calibrated in slot 1 NOTE displayed channel number on the Model 2790 is made up of the slot 1 or 2 and module channel Examples 102 Slot 1 channel 2 216 Slot 2 channel 18 Key press sequences Test procedures for front panel operation are presented as key press sequences For example the following
115. resistance oxide that diminishes the ability of the shunt bar to act as an effective short across the bridgwire s Without a good contact short detonation could occur The measured resistance of a shunt bar is typically between 10 to 100mQ One method used for the shunt bar test is shown in Figure 1 2 In this case the dry circuit mode of the 7751 7752 7753 clamps voltage at 20mV 1mA maximum for the constant test current of the I source This low voltage will not pierce the oxide With the low ohms math function SxIohms selected the reading can be read directly from the dis play of the Model 2790 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 1 7 Figure 1 2 Shunt bar testing Keithley i 17751 7752 r 1221 or 7753 i 1221 Module Shunt Bar Under 2790 VMEAS 1221 SOURCE lest DMM RSHUNT 1 i RsHUNT es ME i i i 1 E REND Petes tae iri NOTE lfrequired a more accurate resistance measurement of the shunt bar can be NOTE achieved by disabling the dry circuit and using a test current of 50mA An even more accurate resistance measurement can be achieved using the Q4 function of the Model 2790 Keep in mind that this is an additional test and does not replace the test using the dry circuit Use this 2 step pro
116. rror Trigger delay 400ms Trigger delay 0 10 Sample count 1024 DETector BANDwidth 300 with nPLC 0 01 Maximum useful limit with trigger delay 175ms Typical uncertainties Typical represents two sigma or 95 of manufactured units measure lt 0 35 of reading and three sigma or 99 7 lt 1 06 of reading 14 For signal levels gt 2 2A add additional 0 4 to of reading uncertainty Internal Scanner Speeds Into and Out of Memory to GPIB 7702 Scanning DCV 60 s Internal Scanner Speed Notes Speeds are 60Hz or 50Hz operation using factory default conditions RST NPLC 0 01 Auto Zero off Auto Range off and Display off Sample count 1024 Includes measurement and binary data transfer out GPIB GENERAL SPECIFICATIONS POWER SUPPLY 100V 120V 220V 240V LINE FREQUENCY 50Hz to 60Hz and 400Hz automatically sensed at power up POWER CONSUMPTION 28VA OPERATING ENVIRONMENT Specified for 0 C to 50 Specified to 80 at 35 Altitude up to 2000 meters STORAGE ENVIRONMENT 40 C to 70 BATTERY Lithium battery backed memory 3 years 4 23 WARRANTY year EMC Conforms to European Union Directive 89 336 EEC EN6 1326 1 SAFETY Conforms to European Union Directive 73 23 EEC EN61010 1 CAT I VIBRATION MIL PRF 28800F Class 3 Random WARM UP 2 hours to rated accuracy DIMENSIONS Rack Mounting 89mm high 213mm wide 370mm deep 3 5 in
117. s gt 1GQ it is recommended that the DUT be con nected between two different banks for example Bank 1 and Bank 3 as seen in test connection figures to reduce the possibility of measurement errors caused by leakage resistance Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 24 Model 2790 SourceMeter Switch System User s Manual HIPOT test This test is used to measure the leakage resistance between an initiator bridgewire and the housing Single stage inflator connections to the 7751 7753 module is shown in Figure 5 3 while dual stage inflator connections are shown in Figure 5 5 NOTE The interlock of the 7751 7753 must be enabled in order to use the V source Figure 5 6 shows how interlock is enabled Test circuit The circuit for the HIPOT test is shown in Figure 5 12 Internal shunts The HIPOT test is usually performed with the shunt bar installed This shorts the bridgewire to prevent accidental ignition of the inflator However if the short bar is not installed or should it become defective the protection is gone Therefore the 7751 7752 and 7753 provide built in shunts They can be used in lieu of or with the shunt bars to provide additional safety As shown in Figure 5 12 closing channel 3 or 6 connects the internal shunt across the bridgewire Single stage inflator Closing input channel 1 connects the first bridgewire Dual stage inflator C
118. s have cables attached when manufactured such that the open end of the cables also have shorting clips These clips are pneumatically pushed open during E check testing just after the clips resistance as a short is measured Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 1 4 Model 2790 SourceMeter Switch System User s Manual Model 2790 configurations Model 2790 test configurations available from Keithley include the following 2790 H configuration one 7751 module This test system includes a single 7751 module This module has a programmable 50 to 500 V source and I V amplifier for HIPOT testing It also has a programmable 0 to 50mA constant current I source to measure the resistance of shunt bars and bridgewires 2790 HH configuration two 7751 modules This test system includes two 7751 modules When used with a left and right type station this two module high voltage system allows higher throughput for increased efficiency When used with a left and right type station this two module high voltage system allows two inflators to be tested It provides higher throughput for increased effi ciency When soaking is required for HIPOT testing one inflator can be tested while the other inflator is soaking high voltage applied Fora dual inflator the two high voltage module system allows parallel soak and test of each half 2790 HL configuration o
119. sconnected The interlock of the 7751 7752 7753 module must be enabled in order to connect the I source or V source 7751 7753 to the rest of the switch matrix With interlock disabled you will not be able to close switches that connect the selected source to the DUT and DMM The typical test station has a built in interlock switch which is to be connected to INTERLOCK of the 7751 7752 7753 When the test station lid or safety shield is open the switch will open to disconnect the sources of the 7751 7752 7753 Figure 5 6 shows how to connect the interlock of the 7751 7752 or 7753 to the test station Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 10 Model 2790 SourceMeter Switch System User s Manual NOTE As shown in Figure 5 6 only connect a switch to J106 Do not connect any external sources to it The internal 5V source for interlock is referenced to chassis earth ground If the 5V terminal of J106 comes into contact with earth ground a fuse on the module will open After the fault is cleared the fuse will reset automatically With interlock open the following channels will open and cannot be closed e Channel 21 With this channel open the selected source is isolated from the rest of the module e Channels 18 and 19 With these channels open the backplane of the Model 2790 is isolated from the switching module Open interlock errors Details on open i
120. se the Model 2790 to automatically scan through the specified memory locations As each memory pattern is scanned the sources and DMM are configured appropriately the specified group of channels is closed and a reading is taken Reading limits can also be assigned to each memory pattern so that during a scan the readings will automatically be inspected for PASS FAIL conditions Digital outputs corresponding to these conditions are also available NOTE Memory patterns be used only with the following functions DC volts 2 wire ohms and 4 wire ohms Front panel operation Memory patterns cannot be defined from the front panel but they can be recalled once defined by remote commands see below To recall defined memory patterns from the front panel Press CLOSE 2 Usethe RANGE A and keys to select CLOSE MEMORY then press ENTER 3 Use lt q gt and V to select the memory pattern number 1 40 then press ENTER Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Memory pattern commands 2 21 Memory patterns commands are summarized in Table 2 5 See Section 2 of the Model 2790 Reference Manual for details on these commands Command ROUTe MEMory CHANnels n lt clist gt ROUTe MEMory SOURce LEVel n lt NRf gt lt clist gt ROUTe MEMory DELay n lt NRf gt ROUTe MEMory REC
121. sistance 2 wire ohms measurement accuracy can be reduced by the resistance of the protective fuses on the 7751 7752 7753 modules which are in series with the DMM current source output See Fuse resistance consider ations page 6 2 for more information Test circuits The test circuits to verify contact are shown in Figure 5 9 single stage inflator and Figure 5 10 dual stage inflator Contact is checked by performing a continuity check through the V source test leads and the connection points Single for the stage inflator As shown in Figure 5 9 there are three contact connection points V source test circuit Contact checks are performed as follows Bank HI contact Close channels 1 14 and 18 to check the connection at the HI terminal of the bridgewire Bank 2 housing contact Close channels 8 15 and 18 to check the connection at the housing of the inflator Dual stage inflator As shown in Figure 5 10 there are four contact connection points for the V source test circuits Contact checks are performed as follows Bank 1 HI contact Close channels 1 14 and 18 to check the connection at the HI terminal of bridgewire A Bank 2 housing contact Close channels 8 15 and 18 to check the connection at the housing of the inflator Bank 3 HI contact Close channels 4 14 and 18 to check the connection at the HI terminal of bridgewire B Test Equipment Depot 800 517 8431 99 Washing
122. ss EXIT or ENTER 3 Select and enable CALC1 FORM S1I Press SHIFT gt press MATH gt select the low ohms cal CALC1 STAT ON SIIOHMS culation 4 Close channels to ROUT MULT CLOS Press CLOSE gt select MULTI gt select test bridgewire 8101 102 117 101 gt select 102 gt select 117 gt select 118 124 121 118 gt select 124 gt select 121 gt press EXIT 5 Verify channels ROUT MULT CLOS Press SHIFT press CARD select that are closed VIEW gt select SLOT1 7751 7752 or optional 7753 Press EXIT when finished 6 Perform measure READ Take reading from display ment 7 Open all channels ROUT OPEN ALL Press OPEN gt select ALL Test step notes 1 Resetting the 2790 opens all channels selects the function range and selects the I source of the 775 1 7752 7753 mod ule For remote programming RST places the 2790 in the one shot trigger mode For front panel operation FACT defaults places the 2790 in the continuous trigger mode This step sets the I source to output ImA Do not use a higher test current for this dry circuit test For front panel operation and 7751 7753 module the V source output setting will be displayed after setting the I source output This step selects the low resistance calculation Vyas Isour Selecting SIIOHMS sets DMM to 1V range This step closes the channels to make the test connections for the shunt bar test It assumes shunt bar
123. stEquipmentDepot com 6 10 Model 2790 SourceMeter Switch System User s Manual Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Specifications Models 2790 7751 7752 7753 and 7702 Models 2790 7751 7752 7753 specifications Provides the complete instrument specifications for the Model 2790 SourceMeter Switch System including the specifications for the Models 7751 7752 and 7753 modules Ohms specification calculations 7751 7752 7753 Provides equations to calculate ohms specifications for source levels not specified in the 7751 7752 7753 module specifications Model 7702 specifications Provides the complete specifications for the Model 7702 module Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications 7751 7752 7753 SOURCE SWITCH MODULE SPECIFICATIONS 2790 Resistance Mode Specifications with Cards Module function accuracy specifications are for 2 years 23 C 5 C Typ Open Source Maximum Ckt Accuracy Temperature Coefficient Current Resistance Voltage Rdg Ohms 0 18 amp 28 40 50mA 200 5 5 0 09 40mQ 0 002 3mQ C 20mA 50Q 5 5V 0 11 40mQ 0 003 3mQ C 10mA 1000 5 5 0 16 40mQ 0 004 3mQ C Dry Circuit Ohms max with 7751 7752 or 7753 ImA 100 20mV 1 10 40mQ 0 026 3mQ C 7751
124. stitute ANSI states that a shock hazard exists when voltage levels greater than 30V RMS 42 4 peak or 60VDC are present A good safety practice is to expect that hazardous voltage is present in any unknown circuit before measuring Operators of this product must be protected from electric shock at all times The responsible body must ensure that operators are prevented access and or insulated from every connection point In some cases connections must be exposed to potential human contact Product operators in these circumstances must be trained to protect themselves from the risk of electric shock If the circuit is capable of operating at or above 1000 volts no conductive part of the circuit may be exposed Do not connect switching cards directly to unlimited power circuits They are intended to be used with impedance limited sourc es NEVER connect switching cards directly to AC mains When connecting sources to switching cards install protective de vices to limit fault current and voltage to the card Before operating an instrument make sure the line cord is connected to a properly grounded power receptacle Inspect the con necting cables test leads and jumpers for possible wear cracks or breaks before each use When installing equipment where access to the main power cord is restricted such as rack mounting a separate main input pow er disconnect device must be provided in close proximity to the equipment and within easy reach of
125. tact connection points for the V source test cir cuits Contact checks are performed as follows Bank HI contact Close channels 1 14 and 18 to check the connection at the HI terminal of bridgewire A Bank 2 housing contact Close channels 8 15 and 18 to check the connection at the housing of the inflator e Bank 3 HI contact Close channels 4 14 and 18 to check the connection at the HI terminal of bridgewire B Figure 5 14 Test circuits memory patterns dual stage inflator contact test 2790 DMM 2790 DMM Contact Point 2790 1 of 3 Dual Stage Inflator Q Closed channel switch Test assumptions NOTE Each channel is a 2 pole switch Therefore when a Inflator housing connected to Bank 3 channel is closed two Bridgewire A connected to Bank 1 switches close see Bridgewire B connected to Bank 2 schematic in Figure 2 1 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Test procedure 5 31 The basic test procedure for using memory patterns to perform contact tests on a dual state inflator using scanning is shown in Table 5 7 The same test procedure using individual memory pattern location recall is shown in Table 5 8 This procedure sets up three memory locations for the necessary relay closures Each memory location is set up as follows Delay Os Function 2 w
126. the 20mV dry circuit clamp Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 11 When using the dry circuit test current is automatically limited to slightly more than regardless of the programmed level Therefore it is recommended that the I source output be set to ImA or less to ensure that a known current is being used for the resistance measurement NOTE The Sxlohms math functions use the programmed I source values for their cal culations If the I source output is not set to ImA or less while dry circuit is enabled channel 24 closed these math functions will give incorrect resistance readings NOTE Typically the shunt bar test is usually the first step in the testing process for an inflator The typical test station uses a spring loaded mechanism that automati cally installs or removes the shunt bar Test circuit The circuit for the shunt bar test is shown in Figure 5 7 Note that the 20mV dry circuit clamp is used for this test Figure 5 7 Test circuit shunt bar Keithley 7751 7752 or 7753 i Runta VMEAS BO a ea anao E IsouR i 21 10 1 4 Tor 4 17 18 Input Shunt Bar 1 IsouRcE Under 2790 DMM Test i i Input LO NOTE Each channel except channel 24 is a 2 pole Closed ch switch switch Therefore when a 2 pole channel is Closed chann
127. the following command selects the 2 wire ohms measurement function for memory pattern location 1 SENS FUNC RES M1 Once various attributes are assigned to memory pattern locations those functions will be executed when those memory pattern locations are recalled either individually or while scanning Memory pattern scanning To perform scanning with memory patterns simply include the memory pattern locations in place of channels in the scan list then set up and trigger a scan in the usual manner For exam ple the following command sets up a memory pattern scan for memory locations 1 3 and 5 ROUT SCAN M1 M3 M5 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 2 23 Memory pattern log Table 2 6 provides a log for you to record the stored parameters for each memory location Table 2 6 Memory pattern log Memory location Source level s Delay Channels Functions 1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15 M16 M17 M18 M19 M20 M21 M22 M23 M24 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2 24 Model 2790 SourceMeter Switch System User s Manual Table 2 6 cont Memory pattern log Memory location Source level s Delay Channels Functions M25 M26 M27 M28 M29 M30 M31 M32 M33 M34 M35
128. the operator For maximum safety do not touch the product test cables or any other instruments while power is applied to the circuit under test ALWAYS remove power from the entire test system and discharge any capacitors before connecting or disconnecting ca 5 03 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com bles or jumpers installing or removing switching cards or making internal changes such as installing or removing jumpers Do not touch any object that could provide a current path to the common side of the circuit under test or power line earth ground Al ways make measurements with dry hands while standing on a dry insulated surface capable of withstanding the voltage being measured The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the equipment may be impaired Do not exceed the maximum signal levels of the instruments and accessories as defined in the specifications and operating in formation and as shown on the instrument or test fixture panels or switching card When fuses are used in a product replace with same type and rating for continued protection against fire hazard Chassis connections must only be used as shield connections for measuring circuits NOT as safety earth ground connections If you are using a test fixture keep the lid closed while power is applied to the device under t
129. they are equivalent to the original component Note that selected parts should be purchased only through Keithley Instruments to maintain accuracy and functionality of the product If you are unsure about the applicability of a replacement component call a Keithley Instruments office for information To clean an instrument use a damp cloth or mild water based cleaner Clean the exterior of the instrument only Do not apply cleaner directly to the instrument or allow liquids to enter or spill on the instrument Products that consist of a circuit board with no case or chassis e g data acquisition board for installation into a computer should never require cleaning if handled accord ing to instructions If the board becomes contaminated and operation is affected the board should be returned to the factory for proper cleaning servicing Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Table of Contents 1 Test System Overview 1 2 s anap r i iasi 1 2 Technical terms ei 1 3 Model 2790 configurations remet tienne 1 4 jo T 1 5 Inflator tests 2 122 iecit etr iri been pa ERR 1 6 Shunt bar test crecer sean iere 1 6 Bridgewire test 1 icio epe do 1 8 Insulation resistance HIPOT test 7751 and 7753 only 1 9 2 Keithley 7751
130. to the 7751 7752 7753 module NOTE 7702 allows measurement of external sources but use extreme caution single faults hardwarelsoftware could detonate airbag Screw terminals Screw terminals on the switching modules are used for connection to DUT and external cir cuitry The Models 7751 7752 and 7753 use quick disconnect terminal blocks A terminal block can be wired outside the module and then plugged back in Figure 4 1 shows how to access the screw terminals on the switching module Channel designations for the screw terminals are contained in Figure 4 2 7751 7752 7753 and Figure 4 3 7702 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 4 3 CAUTION For the Model 7751 7753 be sure that the thermal pad is not dislodged Also be sure to use the correct cover with the integral heat sink to assure proper voltage source operation Note that earlier 7751 modules do not have the pad or heat sink Figure 4 1 Screw terminal access Heat Sink Underneath Conductive Thermal Pad LOCK 099965 92525 Cabling requirements General requirements Cable wires should be mechanically dur
131. ton Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 19 Figure 5 9 Test circuits contact check single stage inflator InteimaliOo 062A ern fuses not shown see Section 6 2790 Contact Point DMM 1 of 2 2790 Single Stage DMM Inflator G9 Closed channel switch NOTE Each channel is a 2 pole switch Therefore when Test assumptions channel is closed two Inflator housing connected to Bank 3 switches close see Inflator bridgewire connected to Bank 1 schematic in Figure 2 1 Figure 5 10 Test circuits contact check dual stage inflator Internal 0 062A cL M EE IL C fuses not shown see Section 6 2790 DMM 2790 DMM Contact Point 2790 1 of 3 Dual Stage Inflator Closed channel switch Test assumptions NOTE Each channel is a 2 pole switch Therefore when a Inflator housing connected to Bank 3 channel is closed two Bridgewire A connected to Bank 1 switches close see schematic Bridgewire B connected to Bank 2 in Figure 2 1 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 5 20 Model 2790 SourceMeter Switch System User s Manual Test procedures Single stage inflator Perform the Test Steps in Table 5 3 Dual stage inflator Perform the Test Steps in Table 5 4 WARNING To prevent accidental detonation of the inflator A
132. tput Level Programmable 50 to 500 CH 28 Programming Resolution 100mV Output Current 7751 S0LA maximum for rated accuracy 1mA typical into short circuit 7753 500 maximum for rated accuracy 1mA typical into short circuit System Throughput Connect source measure calculate 0 01 NPLC Filter Off over GPIB Bus High Ohms Source V 13 Rdgs Sec Low Ohms Source I 9 Rdgs Sec 1 NPLC Filter On Over GPIB Bus High Ohms Source V 11 Rdgs Sec Low Ohms Source I 7 Rdgs Sec System Throughput Notes 1 Reset upon fixed Vsource level no settling time HW 11 04 03 Rev D Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications 7751 7752 7753 SOURCE SWITCH MODULE SPECIFICATIONS Ch 1 Source oo Bank 1 Sense oo 1101 Source o o LO Ch 2 Sense 6 2 Alo o o To Model Ch 3 i 2790 B1 Backplane Source Enable Interlock 1 vL 5V J106 Interlock Source o otc 9 1 10 C n Sense eS Bank 2 J102 Guard Source c LO Ch 5 1 o 1195 Sense Source LO A2 i i Ch 6 1 O Sense HI Sense LO Source ooo 9 1 5 Ch 7 3 m WIN ense O rods IV OUT J108 Source c ol Ch 8 1 Sense
133. uracy Typical short circuit current is ImA Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Figure 2 2 Setting I source and V source output levels Press Press Select CONFIG 77xx 7751 7752 7753 SLOT1 77xx SLOT2 77xx Select module 7751 Bu 7751 7752 27 01 00 et source 1 C27 01 00 mA 7752 7753 output 7751 7751 7753 V C28 050 0 V 7753 should be installed in slot 1 for rated accuracy Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 7753 Set V source output V C28 050 0 V 7753 2 7 2 8 Model 2790 SourceMeter Switch System User s Manual Remote programming As shown in Table 2 1 the amplitude command is used to set the outputs of the sources Notice that the channel number of the V source 28 and I source 27 must be included in the command string Table 2 1 Commands to set amplitude for V source and I source Commands Description Default SOURce VOLTage LE Vel IMMediate AMPLitude lt NRf gt lt clist gt Set V source output 50 to 500 V 50V lt clist gt 128 Slot 1 228 Slot 2 AMPLitude lt clist gt Query V source output level SOURce CURRent LEVel IMMediate AMPLitude lt NRf gt lt clist gt Set I source output 0 to 50 mA 0 0
134. ut setting in mA Example Determine temperature coefficient for an I source setting of 30mA of reading 0 001 0 025 30 96 C 0 001 0 00083 0 00183 C Ohms offset 0 001 30 Q C 0 033mQ C Ohms temperature coefficient 30mA 0 00183 0 033m C 7751 7753 V source High ohms specifications using the V source of the 7751 7753 are provided for the 500V and 50 settings Use the following formulas for other V source settings For measurements 1MQ to 10MQ Ohms accuracy of reading 1 1 15 VsourcE Ohms offset 20kQ where Vsourcg is the voltage output setting in volts Example Determine ohms accuracy for a V source setting of 100V of reading 1 1 15 100 1 1 0 15 1 25 Ohms accuracy 100V 1 25 20kQ Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com A 10 Specifications Model 2790 SourceMeter Switch System User s Manual Ohms temperature coefficient TC of reading 0 02 I VsoURCE TC ohms offset 2000 where Vsourcg is the voltage output setting in volts Example Determine temperature coefficient for a V source setting of 100V of reading 0 02 1 100 9o C 0 02 0 01 C 0 03 C Ohms temperature coefficient 100V 0 03 2000 C For measurements 10MQ to 100MQ Ohms accuracy of reading 1 1 60 VsourcE Ohms offset
135. wire can be closed at the same time When you close another input channel the previous input channel opens Channel assignments To control the appropriate switching module the slot number must be included with the switching module channel number The channel assignment is formatted as follows SCH where S is the slot number 1 or 2 CH is the channel number Examples 101 Slot 1 Channel 1 218 Slot 2 Channel 18 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual Front panel operation For system channel operation there are two methods to close an input channel You can use the lt and gt keys or the SINGLE option for the CLOSE key The OPEN ALL option for the OPEN key opens all channels 4 and p gt keys These front panel keys Figure 3 6 can be used to select the next or previous input channel Figure 3 6 lt q and gt keys GT gt Close previous E S Close next input channel input channel With the first 7702 input channel closed displayed pressing the lt key opens the closed input channel With the last 7702 input channel closed displayed pressing the key opens the closed input channel CLOSE key As shown in Figure 3 7 the SINGLE option of the CLOSE key can be used to close an input channel while the MULT option can be used to close multiple channels Figure 3 7 CLOSE key A
136. with plug in modules only Auto zero off For LSYNC On line frequency 0 1 For LSYNC Off use 60dB for gt 1PLC For 1kQ unbalance in LO lead 14 Speeds for 60Hz 50Hz operation using factory defaults operating conditions RST Autorange off Display off Limits off Trigger delay 0 S Speeds include measurements and binary data transfer out the GPIB 16 Sample count 1024 auto zero off 17 Auto zero off NPLC 0 01 8 For lead resistance gt 00 add the following uncertainty Q for measurement temperatures of 1 70 100 C 100 150 2 2kQ 44004 0 22 C 1 11 C 5 0kQ 44007 0 10 C 0 46 C 10kQ 44006 0 04 C 0 19 C HW 11 04 03 Rev D Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com 2790 SourceMeter Switch System Specifications MAINFRAME FUNCTION SPECIFICATION AC MEASUREMENT SPECIFICATIONS All Ranges Accuracy of reading of range 23 C 5 C All Ranges 3 Hz 10 Hz 20 kHz 50 kHz 100 kHz Function Range Resolution Calibration Cycle 10 Hz 20 kHz 50 kHz 100 kHz 300 kHz Voltage 100 0000 mV 0 1 uV 90 Days 0 35 0 03 0 05 0 03 0 11 0 05 0 6 0 08 4 0 4 0 5 1 000000 V 1 0 10 00000 V 10 pV 1 Year 0 35 0 03 0 06 0 03 0 12 0 05 0 6 0 08 4 0 0 5 100 0000 V 100 750 000 V 1 0 Temp Coeff C 0 035 0 003 0 005 0 003 0 006 0 005 0 01 0 006 0 03 0 01 3 Hz 10
137. ws that secure the module in the mainframe Tightening these screws connects the module to chassis ground Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Inflator Testing Introduction Summarizes the tests used for airbag inflators and provides notes that apply to most tests Test system Shows a typical system connection using a programmable logic controller PLC and a PC Test signal connections The four basic system test connection schemes for inflator testing e Interlock Covers interlock which is used to disconnect the sources of the 7751 7752 and 7753 modules from the switch matrix Shunt bar test Provides the test circuit and procedure to measure the resistance of a shunt bar Bridgewire tests Provides the test circuit and procedure to measure bridgewire resistance of an inflator Insulation resistance HIPOT tests 7751 7753 only Provides the test cir cuits and procedures to measure the insulation resistance of an inflator Summa rizes cable discharge Includes tests for contact checks for high voltage connections and V source readback verification source readback Shows how to use the I source readback circuit to verify the actual current flowing in the test circuit for bridgewire and shunt bar tests Memory patterns test Gives a test example using the memory patterns feature which can be used to simplify
138. x 8 375 in x 14 563 in Bench Configuration with handle and feet 104mm high x 238mm wide x 370mm deep 4 125 in x 9 375 in x 14 563 in SHIPPING WEIGHT 6 5kg 14 lbs DIGITAL I O 2 inputs 1 for triggering and 1 for hardware interlock 5 outputs 4 for Reading Limits and 1 for Master Limit Outputs are TTL compatible or can sink 250mA diode clamped to 33V EARTH ISOLATION 500Vpeak gt 10GQ and lt 150pF any terminal to chassis TRIGGERING AND MEMORY Window Filter Sensitivity 0 01 0 1 1 10 or Full scale of range none Reading Hold Sensitivity 0 01 0 1 1 or 10 of reading Trigger Delay 0 to 99 hrs 1ms step size External Trigger Delay lt 2ms External Trigger Jitter lt lms Memory Size 55 000 readings MATH FUNCTIONS Rel Min Max Average Std Dev Peak to Peak of stored reading Limit Test 96 mX b and m 1 X b with user defined units displayed REMOTE INTERFACE GPIB IEEE 488 2 and RS 232C SCPI Standard Commands for Programmable Instruments ACCESSORIES SUPPLIED User Manual and Reference Manual Screw Driver MODULES SUPPORTED Models 7751 7752 and 7102 Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com HW 11 04 03 Rev D 8 Specifications Model 2790 SourceMeter Switch System User s Manual Ohms specification calculations 7751 7752 7753 Ohms specifications for the 7751 7752 7753 module provide th
139. xample using scanning Command Sequence Set up memory location 3 ROUT MEM CHAN 3 108 115 118 ROUT MEM DEL 3 0 SENS FUNC RES M3 SENS RES RANG 100 M3 SENS RES NPLC 1 M3 ROUT MEM READ STAT 3 ON Set up to scan trigger scan store readings ROUT SCAN M1 M2 M3 TRIG SOUR IMM TRIG COUN 1 SAMP COUN 3 TRAC CLE TRAC POIN 3 TRAC FEED CONT NEXT ROUT SCAN LSEL INT INIT Wait for scan to complete before continuing ROUT SCAN LSEL NONE TRAC FEED CONT NEVER ROUT OPEN ALL FORM ELEM READ TRAC DATA Description Set channels 8 15 and 18 for memory location 3 Set delay to 0 Select 2 wire ohms Select 1000 range Select 1 PLC Enable reading Set up scan for three memory locations Immediate trigger source Trigger count 1 Sample count 3 Clear buffer Store three readings in buffer Enable buffer Enable scan Trigger scan Disable scan Disable buffer Open all relays Send readings only from buffer Request all buffer readings Test Equipment Depot 800 517 8431 99 Washington Street Melrose MA 02176 TestEquipmentDepot com Model 2790 SourceMeter Switch System User s Manual 5 33 Table 5 8 Command sequence for memory patterns test example using individual memory pattern recall Command Sequence Description RST Restore GPIB defaults ROUT MEM CLE ALL Clear all memory pattern locations Set up memory location 1 ROUT MEM CHAN 1

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