USER'S MANUAL
Contents
1. If a sensor has high loss the transmitter needs more time to warm up because it is operated at high power The number of times the TRGx LEDs flash can not be directly translated into sensor loss since it is given with respect to that particular channel s dynamic range Dynamic range may vary due to variations of the opto electronic components However it shows how that particular sensor is handled by that interface channel If the TRGx LED flashes at least two times and no more than nine times during the warmup time there is at least a 3 dB reserve and operation can generally be considered to be safe regardless of the exact sensor loss and the particular interface used As long as the sensor loss is signaled by flashing TRGx LEDs the ERRx LEDs continue flashing at 8 Hz showing the warmup time has not yet expired and the interface is not yet operational After the ERRx LEDs are switched off and the TRGx LEDs are continuously on the startup process is complete 3 2 2 Timing 3 2 2 1 Program cycle time The main loop of the program is executed during a constant time interval of approximately 500 us This time can vary about 5 due to the tolerance of the clock oscillator All quantities are updated at every cycle The time resolution of the interface is therefore equal to the program cycle time 15 SL MD 220 User s Manual SENS R LINE 3 2 2 2 Watchdog Timer The watchdog timer is serviced every time the main loop is executed2. 2 2 2 2 Driving Loads When there are no high impedance inputs that inhibit the flow of current it is not necessary to generate a voltage In this case the optocoupler output can be used as a switch to turn current on and off The wiring below shows how to operate an LED or drive optocoupler inputs or relays The current must be limited to a maximum of 50mA with an appropriate resistor R Terminal Terminal o LED NN Driving a LED 2 5 RS 232 Interface The MD 220 has a three wire RS 232 interface with a male 9 pin DSUB RS 232 connector It behaves like a PC sending data on the TXD line Pin 3 and receiving on the RXD line Pin 2 It can be connected directly to a printer with a standard RS 232 cable To connect it to a PC a null modem cable is required similar to the connection between two PCs Please refer to the software section for the communication parameters as baud rate parity etc SL MD 220 User s Manual SENS R LINE 2 5 1 Connector 2 5 2 Wiring MD 220 RS 232 device Female Connector Male Connector Standard RS 232 Cable MD 220 PC 5 GND 1 Female Connector Female Connector Null Modem Cable 10 SL MD 220 User s Manual SENS R LINE 2 6 Reset Switch Pressing the reset switch causes a hardware reset of the microcontroller 2 7 Jumpers The jumpers J1 and J2 are connected to I O pins of the microcontroller They are used to signal different conditions in order to modify
3. H c c O o o Eil poe gt Ge ol A KK A 5 PAK 5 Sg cH ES Dep ES oo SH jx 6H x SG SS x E DS EAR D c eo EN ei mo EN mo EN e 30 s g5 s lS ei SYD v Ze 2 Zo 5 O ol O at 2 0 SIE 3 O The first 3 digit hex number gives the number of seconds elapsed since the last reset It is reset to zero every hour its maximum value is EOFh 3599 The second number is the number of milliseconds which is zeroed when the second count changes Its maximum value is therefore 3E7h 999 The following two 4 digit hex numbers give bit wise information about the status of each channel Their meaning is as follows Bit0 LSB TRIGGERED Channel is currently detecting load trigger signal is on Bit 1 TRG_TIMEOUT Trigger signal has been on for 30 s and will now be cleared trigger threshold will be reset Bit 2 TRG_INHIBIT Trigger signal inhibited Bit 3 reserved Bit 4 ANALOG_LOW ANAx voltage requires upward adjustment Bit 5 ANALOG_HIGH ANAx voltage requires downward adjustment Bit 6 ANALOG_DOWN ANAx voltage too low for proper triggering Error Bit 7 ANALOG_CLIPPED ANAx voltage too high for proper triggering Error Bit 8 THRSH_NOUPDATE Updating of trigger threshold is inhibited due to expected load detection Bit 9 THRSH_TIMEOUT Trigger threshold has not been updated for 30 s and will be updated now Bit 10 THRSH_RESET Trigger threshold is considered to be wron
4. Low Resistance Sensor Failure 4 AUX1 Auxiliary Optocoupler Output 1 bi AUX1 Low Resistance TRG1 AND TRG2 6 O TRG2 Trigger Channel 2 Optocoupler Output 7 TRG2 Low Resistance Load Response 8 TRGI Trigger Channel 1 Optocoupler Output 9 TRG1 Low Resistance Load Response 2 4 2 1 Power Supply Terminal Terminals 0 and 1 of the system terminal block are for connection of a 12 24 VDC power supply The MD 220 has built in voltage regulators and is reverse voltage protected The interface draws a maximum of 140 mA Connect the negative output to Terminal 1 and the positive output to Terminal 0 SL MD 220 User s Manual SENS R LINE 2 4 2 2 Optocoupler Outputs 2 4 2 2 1 Internal Circuitry 100 Ohms A gt Terminal H11G1 Optocoupler 68 V gt Terminal The above schematic shows the internal circuitry of the TRG1 amp 2 and AUX1 amp 2 optocoupler outputs When the phototransistor is illuminated by the LED ON condition current flows into the terminal and out of the terminal The resistor limits the maximum allowable current to 50mA Therefore any DC voltage applied directly to the outputs must not exceed 5V when the phototransistor is conductive because the maximum power the 100 Ohm resistor can dissipate is 250mW When the phototransistor is not conductive the maximum voltage is limited by the zener diode to 68V If a voltage above that value is applied even with additi
5. Monitor Voltage or Vmonx with a resolution of 12 Bits An additional DAC controls the light power fed into the sensor Both voltages can be measured at test pins Since the sensitivity of the photodiode is about 0 5 A W the incoming light power can at any time be calculated using the formula p oW Vu _ Vanax A 470kQ 7 5MQ 1 3 Technical Data Device Type MD 220 Hardware Hardware Version 1 1b Number of Channels 2 Size 100x110x19 mm 3 54x4 33x 75 in Electrical Connections 10 wire screw terminal block RS 232 3 wire 5 test points Optical connections SMA 905 LED Peak Output Wavelength 850 nm NIR 660 nm VIS red Maximum Sensor Loss 30 dB NIR 20 dB VIS Relative Humidity 80 at 25 C 77 F Temperature Range 40 C to 85 C 40 F to 185F Supply Voltage 12 to 24 VDC Supply Current lt 140 mA Analog Output at Test Points 0 10 V Optocoupler Outputs max OFF 50V lt 1uA ON 5V 50 mA 250 mW 25 C RS 232 connector 9 pin DSUB male Velocity Range 1 to 250 km h 0 6 to 155 mph Feeder Length up to 250 meters 820ft Comparative Laser Class 3A NIR sensor disconnected EMV EMI Meets CE requirements Software Program Name MA220STD Program Version 1 2 Program cycle time 500 us 5 Watchdog expiration time A ms Triggering Threshold 0 8 change of light transmittance Hyste
6. computer checks the loss of connected sensors This cannot be derived from the analog and monitor voltages alone because these do not contain any information about the light power fed into the sensors When a t or a T is received the MD 220 continuously reports the sensor transmittances with two four digit hex numbers every line The message format is XIXIXI X XIXI X X CRILF QO g o es O O cs E nes clo ao 85 S oa E N os elo EEL LS EEL oo 8 Cc Cn D lt Cn D X p c oO S CD LI Da ol OSs ZAK Ee O Unlike the logarithmic sensor loss which is given in dB and signaled by the TRGx LEDs on startup the sensor transmittance is a linear quantity which is given in arbitrary units here The theoretic dynamic range of the interface is represented by values from 4h 4 to D8Fh 3471 It must be noted that errors are not signaled exactly when these values are exceeded because the conditions which define an error are not derived from this quantity 19 SL MD 220 User s Manual SENS R LINE 3 2 5 3 4 Status Mode This is a non continuous output mode Itis entered on receipt of an s or an S The status of each channel of the MD 220 is internally described by two status bytes Every time one of these four bytes changes a status message is issued The message format is XIX X X X X XIX X X X X X X CRILF 5 ga E S o s
7. of the common labeling of some of them their behavior is not the same This might be confusing at first but provides maximum convenience during operation 3 2 4 1 Status LEDs There are three groups of status LEDs TRGx AUXx and ERRx The TRGx LEDs show the trigger status of both channels the red ERRx LEDs report error conditions and the AUXx show other conditions or events The TRGx LEDs correspond to one channel each During initialization when the interface is adjusting itself they are flashing up to ten times giving a measure of the sensor loss See also paragraph 3 2 1 on page 15 They are on if the respective channel is ready to detect load and go off when load a load is detected or when an error occurs The ERRx LEDs are also associated to one channel each During initialization they are flashing If the controller cannot transmit enough light through a sensor the respective ERR LED is switched on continuously The AUX1 LED is on when both channels are detecting load otherwise it is off 16 SL MD 220 User s Manual SENS cJR LINE The AUX2 LED comes on when either of the channels has an error condition and its ERR LED is on continuously This might seem redundant but the AUX2 LED is switched on and off in accordance with the AUX2 optocoupler output which reports an error see below This is convenient for troubleshooting purposes 3 2 4 2 System Terminal Block The system terminal block has four optocoupler out
8. or known to be hanging The command can also be given by the host computer if it knows there can be no load on the sensor from another detector i e a inductive loop Using this feature will make malfunctions or anomalies virtually impossible 21 SL MD 220 User s Manual SENS R LINE The command should not be used to acknowledge a trigger signal by clearing it since the load may not have reached its maximum value yet If the trigger threshold is reset while the load increases a second trigger signal might be erroneously generated by the still increasing load Important notice All the information contained herein is believed to be accurate and reliable However SENSOR LINE assumes no responsibility for its use or for any infringements of patents or other rights of third parties that may result from its use No license is granted by implication or otherwise under any patent rights of SENSOR LINE GmbH SENSORLINE shall not be liable for any special incidental or consequential damages related to the use of the product Our product guides and instructions are continuously updated Make sure you have got the latest edition For further information contact the SENSOR LINE technical support team 22
9. subtract an offset of up to 16 times the range of the amplifiers from their input current With growing sensor transmittance the light power fed into the sensors is reduced in order to avoid clipping of the signal When the minimum value is reached the controller compensates for further increases in sensor transmittance by subtracting increasing portions of the photo current before the remainder is fed into the amplifiers see paragraph 1 2 on page 4 After startup the program uses these methods to adjust the amplifiers output voltages called analog voltages to a value in the upper region of the ADCs measuring range Then it establishes a threshold below that value corresponding to a constant fraction of the light detected After this initialization process the program enters its main loop Here it monitors the analog voltages and checks if they have dropped below the threshold values thus signaling load being applied to the sensors As long as there is no load detected the thresholds are carefully adapted to slow changes drifting of the detected light and the analog voltages are adjusted if necessary However if there is load this process cannot be continued since it is impossible to determine whether a change of the detected light is due to drifting or due to a change of the load As equipment does not stop drifting when there is load on the sensor the interface cannot be allowed to detect load for infinite time If during load detection th
10. 95 corresponding to a voltage of approximately 10V This output can be logged and later processed into suitable diagrams When reading it into Microsoft EXCEL all fields must explicitly be marked as text format otherwise numbers that do not contain any letters will be imported as decimal numbers 18 SL MD 220 User s Manual SENS R LINE 3 2 5 3 2 Percent Mode Percent mode is entered as soon as the MD 220 receives a p or a P It continuously reports the relative difference of the registered light power to that which is related to the currently established trigger threshold The message format is X X X X X X CRILF Ei Q x Ex 2z 188 II G ES 00 a om E S N ls Ic Bd Dg c 2E x SLE _ s22 cC 2 939 Ke xe bg ge 5550 505 e B C BCom Pg Oo oc Oo cc Silke gl O The values are given in units of 0 1 For example if the trigger threshold is set to 0 8 the values issued should be around 008 As soon as the sign changes to the interface will trigger This output mode allows for quick judgment of the measuring effect especially the quality of the sensor setup on site without any computations The signal resolution is significantly lower than that obtained from voltage data but the messages are shorter so there is a higher time resolution in percent mode 3 2 5 3 3 Transmittance Mode With this output mode a host
11. Its time interval is set to 4 ms If the program hangs for whatever reason and this time expires a program reset is performed 3 2 2 3 Trigger Timing The trigger function works with a threshold that has a hysteresis of only 2 digits This is just sufficient to prevent the interface from bouncing due to the sheer quantization error of the ADC Debouncing is done by requiring a valid load pulse have at least 3 program cycles 1 5 ms of duration This requires that the trigger delay also be 1 5 ms The output pulse duration is correct because switching off and on is subject to the same conditions With software version 1 1 the output pulse duration can be forced to a minimum value of 20ms regardless of the input pulse duration If jumper J1 is shorted the output will be on for at least 20 ms Without jumper J1 shorted the minimum output pulse duration is 1 5 ms The maximum output pulse duration is 30 s This is the maximum detection time explained in paragraph 3 1 After 30s the interface is freshly adjusted and ready to detect a new load 3 2 3 Jumper Settings When jumper J1 is shorted during reset the trigger output on time is forced to a minimum of 20 ms This feature does not work in software versions prior to 1 1 Shorting jumper J2 sets the baud rate of the RS 232 interface from 9600Bd to 19200Bd 3 2 4 Status Outputs The status outputs are the six status LEDs and four optocoupler outputs on the system terminal block In spite
12. L MD 220 User s Manual SENS R LINE 3 2 4 Status Outputs neue eier 16 324l Status LEDS rinne na ana EE 16 3 2 4 2 System Terminal Bl cken 17 3 2 4 3 Status Table 17 325 RS232 Inlefface uun u anne 18 ER A EE 18 3 2 5 2 Comm Parametere 18 325 23 QUMPUT OS ran arena 18 42 323 1 Voltage Mode na een u 18 3 2 5 3 2 Percent Mode EE 19 3 2 5 3 3 Transmittance Mode 19 3 25 34 Status Oe EE 20 325 3 OP Oe e EE 21 3 2 5 3 6 Software Version Ouenm EEN 21 3 2 5 3 7 Special Output E 21 3254 Commands EE 21 3 2 5 4 1 System Reset Command na 21 3 2 5 4 2 Threshold Reset Commande 21 SL MD 220 User s Manual SENS R LINE 1 General 1 1 Introduction The SENSOR LINE MD 220 is a two channel static opto electronic interface for SENSOR LINE s SPZ SPT fiber optic load sensors This two channel interface supplies light to two fiber optic sensors monitors the amount of light transmitted through the sensors and detects small changes caused by loads applied to the sensors With its advanced circuitry the interface can detect a load on a sensor for as long as it is applied to the sensor The MD 220 incorporates a TI MSP 430 embedded microcontroller programmable via a JTAG interface It has a 10 wire screw clip interface with power supply terminals and four floating optocoupler outputs It also has a RS 232 interface for input and output of data Direct external control is possible through the use of two jumpers and a reset switch Fo
13. SENSLJR LINE Optical Transmittance Analyzer SL MD 220 USER S MANUAL Hardware Version 1 1b Software Version 1 2 SENS gt JR LINE Sensor Line Gesellschaft f r optoelektronische Sensoren mbH Carl Poellath Str 19 D 86259 Schrobenhausen Germany Tel 49 0 8252 8943 0 Fax 49 0 8252 8943 11 Email sensorline sensorline de www sensorline de SL MD 220 User s Manual SENS R LINE Table of Contents 1 Gele u ee 4 Ba We ee EE A 1 2 Principle of Operation E 4 1 3 Technical Eege 5 HN IN EI en een 6 2 1 Dimensional A DEE 6 22 Handling Presautions tte ee u 6 Cer SE e ee een 7 2 4 System BET een een 7 24 1 E ee E 7 242 CONNECUOMS zes er EE 7 2 4 2 1 Power Supply SRI esses seen ea 7 2 4 2 2 Dplocdupler elt ET 8 2 4 2 2 1 Internal Circuitry E 8 2 4 2 2 2 External Wiring WE 8 2 4 2 2 2 1 Generating Voltage Output Signals 22444ss44 nenne nerne nenene 8 242222 Driving Loads ante eee 9 2 5 RS 232 Interface een 9 2 8 1 EE zieren 10 29 2 WINNI EE 10 2 6 Reset E 11 27 S NDE ee bee ee ee 11 See 11 29 Measunng PINS ee ee 12 2 10 Fiber Optic Receptacles nun 12 2 11 WEEN EE 13 3 Software Section au ae 14 3 1 General Description 14 32 ee ee R a a EA 15 3 2 1 Startup Re ET 15 322 MN e ee ere A E ee 15 3 2 2 1 Program cycle ME rnise riren iunda a ee e 15 3 2 22 Watchdog TIME EE 16 322 3 Migger TIMING iaci nta n aa A ara aAa EE AS 16 3 2 3 Jumper Settings ER 16 S
14. UX2 LED The AUX2 optocoupler output becomes conductive and the associated TRGx LED flashes ten times at 2 Hz The TRGx LED is then switched off In the case that there is too much light detected which may happen when an interface with infrared transmitters is used in conjunction with a low loss sensor the ERRx and AUX2 LEDs and the AUX2 optocoupler outputs behave the same way but the TRGx LED does not flash If the sensor loss is within a range where the interface can successfully adjust itself the program waits for the transmitter to stabilize its output power This is necessary because during power up the transmitter becomes warm causing a slight decrease in its brightness during the first few seconds Since it is not possible to derive a measure for the sensor loss from the analog voltages at the test pins the interface signals the virtual sensor loss during warmup time It cannot determine the real sensor loss Rather the sensor loss in this cases defines a certain value within an internal theoretic dynamic range of 30 dB For a number of reasons this range can not be fully utilized in practice but the interface sees the loss of the sensors vary within it In order to express this virtual sensor loss the internal dynamic range is divided into ten intervals of 3 dB While the transmitter is warming up the TRGx LED of each channel is flashed from one to ten times The number of times it flashes multiplied by 3dB is the virtual sensor loss
15. e amount of light detected without any load drifted below the stored threshold the interface would no longer be able to notice the load being removed it would hang For this reason there is a maximum detection time of 30 seconds When this time has elapsed the interface performs an initialization process similar to the one at startup The interface is then ready to detect additional load being applied to the sensor The original load effect is regarded as intrinsic sensor attenuation When the original load is removed the threshold is adapted immediately When the sensor is broken or disconnected no light arrives at the receiver and the interface is unable to detect any load If the sensor fails during operation the detected light falls below the threshold and is reported as load being detected Therefore sensor failure during operation is first reported as a load detected and it changes to an error signal after 30 seconds 14 SL MD 220 User s Manual SENS R LINE 3 2 Details 3 2 1 Startup Procedure After power up or when a program reset is initiated the MD 220 first tries to adjust itself to the particular sensors attached This process takes about one second and is signaled by both ERRx LEDs see paragraph 3 2 4 1 on page 16 flashing at 8 Hz If insufficient light is detected i e if there is no sensor connected to a channel or the connected sensor is broken the respective ERRx LED comes on continuously along with the A
16. er the smaller the attenuation DO NOT USE PLIERS The transmitter and receiver connectors are interchangeable for each channel The transmitter connectors are not interchangeable i e a sensor connected for example to Transmitter 1 and Receiver 2 will not work BER SL MD 220 User s Manual SENS R LINE 2 11 JTAG connector The JTAG connector is used for programming the microcontroller at the factory If you are planning to re program the device in the field please contact Sensor Line GmbH for further information 13 SL MD 220 User s Manual SENS R LINE 3 Software Section The following refers to the MD 220 program MA220STD version 1 2 3 1 General Description The program executed by the microcontroller controls all functions of the MD 220 Detecting a load applied to the sensor is difficult because of the large variation in sensor transmittance versus the small amount of transmittance change when load is applied For example if the sensor transmittance could change by a factor of 100 20 dB and the transmittance change caused by a load was 1 1 100 the complete light measuring range would have to be resolved to 1 10000 of its value in order to detect the load This is more than twice the resolution of a 12 bit ADC To overcome this difficulty the microcontroller controls the photo currents detected by the input amplifiers in two ways First it can vary the transmitter currents by a factor of ten Second it can
17. eviously described characters which only change the output sent via the RS 232 interface there are also characters which directly affect the behavior of the MD 220 3 2 5 4 1 System Reset Command On receipt of a capital H a software reset is initiated just as if the reset button had been pressed This is done by sending the controller into a non terminated loop and having the watchdog timer trigger the reset Consequently it may take up to 4 ms until it is executed This command can also be used to verify the watchdog function 3 2 5 4 2 Threshold Reset Commands When the MD 220 receives a 1 or a 2 the trigger threshold of the respective channel is immediately reset This must not be confused with a system reset which causes the complete startup initialization process to be performed Here the interface only accepts the current light level as new no load value and establishes its trigger threshold 0 8 below it The threshold management algorithm used with MA220STD v1 2 is sophisticated This can not keep the interface from hanging if during load detection something reduces the sensor s transmittance permanently The trigger signal will then remain on for 30 s and the interface will be unable to detect any new load cycle during this time The threshold reset command enables a host computer to tell the MD 220 that there is currently no load on the sensor This is useful to clear the trigger signal in situations where the interface is suspected
18. g and will immediately be set to 0 8 below current light level Bit 11 THRSH_NINIT Trigger threshold not initialized trigger signal inhibited Bit 12 SENSOR_HIGHLOSS Sensor loss above dynamic range Error Bit 13 SENSOR_LOWLOSS Sensor loss below dynamic range Error Bit 14 reserved Bit 15 MSB reserved The very first status message is transmitted immediately after entering status mode but this does not mean that something has changed at that moment Every additional s or S triggers a new message without status change 20 SL MD 220 User s Manual SENS R LINE 3 2 5 3 5 Off Mode On receipt of an o an O or a 0 zero the transmission of any messages is inhibited The interface still receives characters and can be switched to another mode at any time 3 2 5 3 6 Software Version Query When the MD 220 receives a q or a Q a short copyright notice including name and version number of the loaded software is issued Enter off mode or status mode before querying the software version If this does not work the software loaded is MA110STD v1 0 3 2 5 3 7 Special Output Modes When one of the characters F C or Y is received the interface enters special output modes which are meant for laboratory use or troubleshooting in special cases The output consists entirely of printable characters but special software is required to decode it 3 2 5 4 Commands Aside from the pr
19. nd troubleshooting purposes as well as for setting up simple measuring systems Please refer to paragraph 2 5 for the wiring of the connector 3 2 5 2 Comm Parameters The standard comm parameters of the MD 220 s RS 232 interface are 9600 8 N 1 9600 Baud 8 data bits 1 stop bit no parity By shorting jumper J2 the baud rate is switched to 19200 Baud 3 2 5 3 Output Modes There are several different possibilities to output useful data via RS 232 Switching between these output modes is done by sending single characters to the MD 220 The easiest way to do so is by using the keyboard on a PC running a terminal program 3 2 5 3 1 Voltage Mode The Voltage Mode is the default mode at startup While operating in another mode the MD 220 enters the Voltage Mode when it receives a v or a V The interface then continuously reports its analog voltages monitor voltages and thresholds The message format is xX X X X X X XIXIX XIXIX A SIS XIX 1X ICRILF Ss w oO o OO GIT ER e 8 EIN 8 o CIN oo o SIN SG Clo co ee 5 92 o o el d SS SIE o ot Aore ADOS Dos lt el a9 0 lt 5 SOD Eis dD as GID a gt E ss T Ze BO Lei oo geseis ei SSL S SED Ota Oam alo Se SO 8a S O Boa 5 9 Se Q2 D 2 De lt lt Ei be O All voltages are given in 12 bits ADC digits with a maximum value of FFFh 40
20. onal resistors the output might appear conductive but the phototransistor is not To avoid any glitches caused by voltage spikes or surges the optocoupler outputs should not be operated with voltages above 50V 2 4 2 2 2 External Wiring The optocoupler outputs are not connected to any voltage source so there are many ways to obtain various kinds of output signals In all cases an external power supply must be added The outputs behave as switches with the restriction that current can only flow in one direction Below are examples of how the outputs may be wired 2 4 2 2 2 1 Generating Voltage Output Signals Voltage output signals are required if high impedance inputs like those on an oscilloscopes are connected The wiring from the diagrams below can be used if the voltage from the available source has the required value or is not critical Terminal lt 10k Terminal Vout Terminal lt Zero output voltage going Positive output voltage going HIGH on ON condition LOW on ON condition SL MD 220 User s Manual SENS R LINE If the voltage available is too high for the intended inputs a second resistor must be added in order to create a voltage divider as given in the schematics below Itis generally safe to choose resistors in the range of 10kQ Terminal o Terminal lt Terminal Zero output voltage going Positive output voltage going HIGH on ON condition LOW on ON condition 2 4
21. puts divided into two groups TRGx and AUXx The TRGx outputs become conductive ON condition when there is load detected by the respective channel This is inverse to the TRGx LEDs The AUXx optocoupler outputs follow the AUXx LEDs The AUX1 output comes on when both of the TRGx outputs are on and the AUX2 output comes on when there is an error condition regardless at what channel 3 2 4 3 Status Table The table below is to summarize the different states the two channels can be in and the according behavior of the status outputs Status Status LEDs Optocoupler Outputs Channel1 Channel2 TRG1 TRG2 AUX1 AUX2 ERR1 ERR2 TRG1 TRG2 AUX1 AUX2 adjust Adjust 7 flash flash adjust Ready i ON flash adjust Detect flash ON adjust Error i ON flash ON ON ready Adjust ON R flash ready Ready ON ON ready Detect ON ON ready Error ON ON ON ON detect Adjust x flash ON detect Ready ON ON detect Detect ON ON ON ON detect Error ON ON ON ON error Adjust ON ON flash ON error Ready ON ON ON ON error Detect ON ON ON ON error Error ON ON ON ON may flash during startup 17 SENS cJR LINE SL MD 220 User s Manual 3 2 5 RS 232 Interface 3 2 5 1 General The RS 232 interface of the MD 220 allows bi directional communication with a host computer or a passive RS 232 device It can be used for debugging a
22. r quicker troubleshooting six LED status displays show the function of the interface and there are five easily accessible test points for analog measurements Power consumption has been minimized by circuitry that operates the transmitter diodes in series while independently controlling the current through each diode The MD 220 comes with two different kinds of transmitter diodes a near infrared diode giving each channel a dynamic range of 30 dB and a more economic visible light diode for a dynamic range of 20 dB The hardware and software for the MD 220 comes in different versions This manual is divided into a hardware and a software section Please ensure that you have the correct version of this manual 1 2 Principle of Operation GND GND The drawing above is a simple circuit diagram of one channel When the photodiode is illuminated with light from the sensor it proportionally sinks a current to the incoming light power This causes the output of the OP to go high so the current is supplied across the 7 5M resistor When the light becomes too bright the OP output is clipped and the controller supplies additional current via the DAC and the 470k resistor until the OP output is unclipped SL MD 220 User s Manual SENS R LINE Small changes of photo current are amplified by the OP by a factor of 7 5 MO 7 5 VIA The controller measures this voltage Analog Voltage or Vanax as well as the voltage produced by the DAC
23. resis 2 digits Minimum input ON time 3 program cycles 1 5 ms Minimum output ON time 3 program cycles 1 5 ms 40 program cycles 20 ms Maximum output ON time 30 s RS 232 Baud Rate 9600 Bd 19200 Bd Data Bits 8 Stop Bits 1 Parity N no parity with jumper J1 shorted with jumper J2 shorted 5 SL MD 220 User s Manual SENS R LINE 2 Hardware Section The PCB version is found on the bottom layer of the PCB This manual is for hardware version 1 1b 2 1 Dimensional Drawing 110 4 331 Through Holes 3 1 122 Q 12 24VDC d S e Z w Channel 1 _ EI Receiver g Alu AUX2 G z H AUX2 a E ele gj AUX1 D Channel 1 JTAG H he g AUX1 EM Transmitter Connector ie Ig TRG2 D o Lo E D O gt Fir I TRG2 cc d Ed MO oa io bei lt x Sie D TRG1 o 8 3 Channel 2 Hio TRG1 2 o Transmitter amp 5 RS 232 Q Channel 2 Connector Receiver Jumpers O on a ei ei ei HH GND MON1 ANA1 MON2 ANA2 TRGI TRG2 AUX1 AUX2 ERR1ERR2 J2 Ji RESET Test Points Status LEDs Reset Switch 120 4 724 Maximum Height 19 748 Dimensions in mm in 2 2 Handling Precautions The MD 220 is delivered without a housing so handle it the same way as a PC card Some of the interface components are sensitive to electrostatic discharge ESD Leave the interface inside its conductive bag until installation Discharge yourself by touching a grounded conductor before touching the in
24. terface The receptacles are either non conductive or grounded and the system outputs have a special protective circuitry It is relatively safe to handle the interface by these parts If conductive spacers are used the interface may be handled by these spaces because the rims of the through holes are also grounded Before pressing the reset switch by hand first discharge yourself The jumpers and LEDs are connected directly to the controller and should never be touched The test points are connected to OP outputs which are also sensitive to ESD Discharge any measuring clips on the GND pin before contacting one of the other test points SL MD 220 User s Manual SENS R LINE 2 3 Installation The MD 220 PCB has four 3 1mm 0 12 through holes allowing it to be mounted on any appropriate flat surface by means of M3 screws At least 5mm 0 2 spacers are recommended to ensure a sufficient gap between the PCB and the mounting surface 2 4 System Terminal 2 4 1 Mechanical The system terminal is a 10 wire screw terminal block which accepts 0 14 1 5 mm 26 16 AWG wires To fasten the screw clips a screwdriver with a blade up to 3 5 mm wide can be used The terminal block can either be a flat or angled design the latter is used if several interfaces are stacked 2 4 2 Connections Pinning Sign Description 0 12 24VDC Supply Voltage 4 O GND Ground 20 AUX2 Auxiliary Optocoupler Output 2 3 0 AUX2
25. the behavior of the interface without re programming it They can also be used as I O connections for special purposes Please refer to the software section of this manual for the different jumper settings 2 8 Status LEDs There is a display of six LEDs controlled by the microcontroller TRG1 TRG2 AUX1 and AUX2 are yellow and ERR1 and ERR2 are red Please refer to the software section of this manual for the meaning of the LED signals 11 SL MD 220 User s Manual SENS cJR LINE 2 9 Measuring Pins itt gi 4 cam There are five test points with 1 3mm 0 05 pins for measuring the analog voltages evaluated by the microcontroller The meaning of these voltages is thoroughly explained in paragraph 1 2 on page 4 Label Signal GND Ground MON1 Monitor Voltage Channel 1 ANA Analog Voltage Channel 1 MON2 Monitor Voltage Channel 2 ANA2 Analog Voltage Channel 2 2 10 Fiber Optic Receptacles Sign Vmont VAnA1 VMON2 Vana2 Two fiber optic load sensors can be connected to the MD 220 via four SMA 905 fiber optic receptacles Viewed from the front the receptacles for Channel 1 are on the left hand side and those for Channel 2 on the right hand side The transmitters are the inner receptacles Do not stare into the transmitters when the interface is powered and there is no sensor connected Fasten the sensor s fiber connectors to the transmitter or receiver by screwing tightly on by hand the tight
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