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WBK17 - Measurement Computing

1. for Encoders snap in terminal block Includes connections for Common 5 VDC and 15 VDC Digital Expansion In HD26 Female amp Digital Expansion Out Digital In Trigger Clock DB25 Female LED Indicators Active Ready and Power Rear Panel Power Switch Power In and Out DINS connectors for 10 VDC to 30 VDC Digital Outputs snap in terminal block with connection for Common and 8 Channels Expansion Control In DB15 Male amp Expansion Control Out DB15 Female Expansion Signal In BNC amp Expansion Signal Out BNC WBK17 Counter Encoder Module 987996 WBK17 pg 1 The WBK17 is an 8 channel multi function counter encoder module that can be used with WaveBook 5 16 512A 516A and 516E systems The WBK17 module can not be used with earlier WaveBook models such as WaveBook 512 and WaveBook 512H Each of the high speed 32 bit counter channels can be configured for counter period pulse width time between edges or encoder modes All channels are capable of measuring analog inputs that are digitized by the WaveBook at up to 1 MHz The Analog Waveform Input Mode can be used to measure waveforms from 0 to 100 V peak to peak 50 V The maximum analog over range is 150 V peak to peak 75 V The resolution is 0 002307 V bit BNC lt m Expansion Signal Out lt Analog g Expansion BNC gt Interface ay Ex pansion Signal In oe pe Expansion me Control Out oo Expansion Control Interface a
2. must be connected to separate channels e The input channel lows must be jumpered to COM e Each encoder ground connects to COM e Up to four encoders can be powered from the Encoder Power Power Out terminal block Refer to your encoder specification sheet for actual power requirements Each encoder power wire connects to the Encoder Power Power Out terminal block s 15 VDC or 5 VDC connector as applicable For Differential Connections For differential applications connections made from the encoder to the WBK17 s front panel are as follows e Signals A B and Z connect to the H channel high connections on WBK17 s Counter Input Terminal Blocks A B and Z highs must be connected to separate channels e Signals A B and Z connect to the respective L channel low connections on WBK17 s Counter Input Terminal Blocks e Each encoder ground connects to COM e Up to four encoders can be powered from the Encoder Power Power Out terminal block Refer to your encoder specification sheet for actual power requirement Each encoder power wire connects to the Encoder Power Power Out terminal block s 15 VDC or 5 VDC connector as applicable For Open Collector Outputs External pullup resistors can be connected to the WBK17 s counter input terminal blocks A pullup resistor can be placed between any input channel and one of the two power supplies 5V or 15V provided by the Encoder Power Power Out terminal
3. For example if the desired input bandwidth is only 0 to 10 kHz then the 20 kHz low pass filter will reduce unwanted noise components of 20 kHz by 3dB Unwanted noise of 200 kHz will be reduced by 23dB and noise components of 2 MHz will be reduced by 43dB Since the analog filters come before the comparator circuit and the expansion analog output path their effects will be observed at the comparator and in the analog waveform scanned by the WaveBook The analog expansion path going back to the WaveBook has a 450 kHz single pole filter WBK17 Counter Encoder Module 987996 WBK17 pg 5 Comparator WBK17 pg 6 Each channel has its own individually programmable comparator as shown in the figure below The output of the filter stage feeds the comparator circuit The analog waveform that is present at the comparator is gain adjusted and then multiplexed onto the WaveBook s analog expansion port This allows the analog input waveform as it appears at the comparator post coupling post filter to be scanned like any other analog waveform The analog path going to the WaveBook is bandwidth limited to 450 kHz The analog path between the input and the comparator is not bandwidth limited unless a low pass filter is used 450 kHz LPF To Wavebook 516 Multiplexer From Filter Stage Comparator To Debounce Programmable peur Threshold Comparator The comparator has a programmable threshold set by the DAC The threshold can be set anywhere
4. block Choose a pullup resistor value based on the encoder s output drive capability and the input impedance of the WBK17 Lower values of pullup resistors will cause less distortion but also cause the encoder s output driver to pull down with more current If the inputs are connected differentially then each channel will need two pullup resistors 1 e one on the low signal input and one on the high signal input WBK17 pg 22 987996 WBK17 Counter Encoder Module Wiring for 1 or 2 Encoders The following figure illustrates differential connections for two encoders For single ended connections remove the A B and Z signal connections and short the Low inputs of these channels to COM The A signals must be connected to odd numbered channels and the associated B signals must be connected to the next higher even numbered channels For example for A connected to channel 1H B is connected to channel 2H A wiring diagram for one encoder is not shown as it would be identical to the following diagram except one of the encoders and its associated wiring would be removed Encoder Power Power Out Terminal Block Encoder 2 Counter Input Terminal Blocks Encoder 1 WBK17 Partial Two Encoders with Differential Connections to WBK17 In addition to the previous figure the following table indicates how to connect two encoders to a WBK17 module Each sig
5. s DB25 Pinout WBK17 Counter Encoder Module 987996 WBK17 pg 29 Digital Outputs The WBK17 has 8 fully programmable digital outputs Each output has an open drain DMOS FET Double diffused Metal Oxide Semiconductor Field Effect Transistor that can sink up to 150 mA and is capable of directly driving relays 4 Volts HEN To WaveBook S16 and Pattern Detection Circuit D Distal Cut D 22 EN S From Digital Control S and Pattern Detection eS DMOSFET neue is a COME Distal Outputs Typical of 8 Channels Snap In Terminal Block The WERE has 5 of these on WERE 17 Eear Panel CoO circuits 1 for each channel Digital Output Port The digital output port can be read back as part of the scan group of an acquisition If the DMOSFET is never turned on by the WBK17 then the digital output port can be used as an input port An external driver can drive any of the digital output bits high or low as long as the WBK17 s DMOSFET is not turned on The digital outputs can be directly updated by application software at any time The digital output port has an 8 bit Mask byte associated with the digital update byte The output port will be updated if the corresponding bit in the Mask byte is a 1 Otherwise the output port bit will be left unchanged The digital outputs can be updated based on the condition of any input channel value s Up to 16 set points each with two 16 bit compare values an 8 bit digital output port byte an 8
6. 1 5 kg 3 1 Ibs Analog Inputs Channels 8 differential Input Connections COM CH high CH low Input Connectors Removable screw terminal blocks 2 channels per block Input Impedance 20 Ohm Single ended 40 K ohm double ended Input Voltage ranges 50V to 50Volts specified 75 Volts to 75 Volts maximum Resolution 0 002307 V bit DC Accuracy 0 25 of reading 200 mV offset Noise 5 mVrms typical 10 mVrms maximum Common Mode Rejection 70 dB typical 0 to 60 Hz 40 dB guaranteed 0 to 60 Hz Coupling AC or DC programmable Analog Sampling Bandwidth DC to 1 MHz Filtering Programmable30 Hz 20 kHz 100 kHz Single pole low pass filter Comparator Input Threshold 12 5V to 12 5V referred to input programmable in 100 mV steps Threshold Accuracy 2 of setting plus 125 mV offset Input Hysteresis 50 mV minimum 100 mV maximum Input Frequency DC to 5 MHz Sensitivity 500 mVpp DC to 1 MHz 5 Vpp 1 MHz to 5 MHz Debounce Module Debounce Times 16 selections from 500 ns to 25 5 ms Positive or negative edge sensitive Glitch detect mode or debounce mode WBK17 Counter Encoder Module Time Base Accuracy 10 ppm 0 to 50 C Five Programmable Modes Counter Period Pulsewidth Timing Encoder Counter Mode Options Totalize Clear on Read Rollover Stop at all Fs 16 bit or 32 bit any other channel can decrement the counter Period Mode Options Measure x1 x10 x100 or x1000 period
7. 967 295 ticks PULSEWIDTH OPT4 Allows the mapped channel to gate the counter When the mapped channel is high the counter is enabled to count When the mapped channel is low the counter is disabled but holds the count value The mapped channel can be any other input channel or one of the detection signals WBK17 Counter Encoder Module 987996 WBK17 pg 17 WBK17 pg 18 Pulsewidth and Timing mode Accuracy Upper 16 bits of the 32 bit Counter Range S Ticksize Averaging Option 800 80000 20000 ize nS 80 8000 2000 s00m 80 Full 32 bit Counter Range S Ticksize nS Averaging Option 10m 80000 20000 1 1m 8000 2000 Pulsewidth and Time Ranges for a 32 bit Value Sampling error is less than 0 2 Full 32 bit Counter lt 10 ppm Range S Ticksize nS Averaging Option 2 80000 20000 200m 8000 2000 High Accuracy Pulsewidth and Time Ranges for a 32 bit Value that has little sampling error lt 10ppm lt Ippm 987996 PULSEWIDTH OPT6 This allows the mapped channel s pulsewidth to be measured instead of the input channel The mapped channel can be any other input channel post debounce or one of the detection signals on any channel This option allows the counter to be used with any other input channel post debounce or with one of the detection signals If the channel s input is used elsewhere for example gating another counter the counter for this channel does not
8. Counter Encoder Module 987996 WBK17 pg 31 Setp curt Data Channel Data CH Low Liit DETECT oetpomt Data Setpoint Data OPTS Setpoint Data Distal Cnutput Port Diet omp DIG Pattern Detection Module Note OPT bits see figure are set by software options Example Setpoint Detection on a Totalizing Counter The figure below shows how 3 setpoints could be defined for channel 1 Channel 1 is shown in totalize mode the counter is simply counting upward The setpoints define points of change for Detect 1 as the counter counts upward The first setpoint High Limitl Low Limit1 dictates channel 1 s detect output to be high when greater than Low Limit but less than High Limitl In this case the channel 1 setpoint is defined for the 16 lower bits of channel 1 s value Channel 1 could be in 16 or 32 bit mode the detect pattern would just repeat every time the lower 16 bit counter rolled over There is another setpoint set by High Limit2 Low Limit2 and then another set by High Limit3 Low Limit3 The last setpoint High Limit3 Low Limit3 dictates that channel 1 s detect output be high whenever Channel 1 s value is greater than HighLimit3 LowLimit3 is ignored The digital output port could be updated on each rising edge of Detect 1 WBK17 pg 32 987996 WBK17 Counter Encoder Module pean ee ope eee eee ase ae eee eee ee E T 65535 HighLimit3 HighLimit2 LowLimit HighLimit Low Li
9. Mode An example One channel s acquired data might be 0 0 0 0 80 80 80 80 79 79 79 79 81 81 81 81 This data represents the number of ticksize intervals counted during the period measurement The first value s returned will be zero since the counters are cleared at the beginning of the acquisition The data comes in sets of four since the scan period is about one fourth as long as the input channel s period Every time the period measurement is latched from the counter the counter is immediately cleared and begins to count the time for the subsequent period If the scan period is a lot slower than the input period the acquired data will be missing some periods To obtain greater resolution you can increase the scan period or use an averaging option see OPT 1 0 The data returned is interpreted as time measured in ticks There are four timebase settings 20 ns 200 ns 2 us and 20 us These are often referred to as tick sizes The WBK17 uses a 50 MHz 10 ppm oscillator as a timing source PERIOD OPT 1 0 Determines the number of periods to time per measurement This makes it possible to average out jitter in the input waveform sampling error noise etc There are four options 1 The channel s measurement is latched every time one complete period has been observed 2 The channel s measurement is latched every time that 10 complete periods have been observed the value that gets returned is equal to 10 consecutive perio
10. and all devices connected to it from power before removing the WBK17 s cover plate Failure to do so could result in electric shock and possible death CAUTION Be careful to avoid component damage while WBK17 enclosure is open Expansion Expansion MOALE Sgnen Expansion Expansion Ea e Control Out Control In Power Power Power lil ipi EEE Eoi Digital Outputs Out In Switch Do y BNC JBNC DB15 0815 gnr Input Power Fuse 4Amp Mini ATO User Replaceable DC DC Converter PTODECANGI Output Power Fuse Output Power Fuse 2A 5V Mini ATO 1A 15V Mini ATO User Replaceable User Replaceable Locations of WBK17 s User Replaceable Fuses WBK17 pg 36 987996 WBK17 Counter Encoder Module WBK17 Specifications General Counter Module Power Consumption 520 mA 15V input 310 mA 25V input assuming no load on power output Input Power Range 10 to 30 VDC Input Power Fuse F201 4A Mini ATO user replaceable Power Output to Quadrature Encoder 5V 10 1000 mA and 15V 10 500 mA Output Power Connector Removable screw terminal block 15V Output Power to Encoder Fuse F1 1A Mini ATO user replaceable 5V Output Power to Encoder Fuse F2 2A Mini ATO user replaceable Operating Temperature 0 to 50 C Storage Temperature 0 to 70 C Vibration MIL STD 810E Category 1 Humidity 0 to 95 RH non condensing Dimensions 285 mm W x 220 mm D x 35 mm H 11 x 8 5 x 1 375 Weight
11. detection module only looks at acquired data not the actual counter value WBK17 pg 26 987996 WBK17 Counter Encoder Module Wiring for 3 Encoders The following figure illustrates single ended connections for three encoders For differential connections we would simply make A B and Z signal connections to the respective channel slots With three encoders it should be noted that there is no separate channel for a third set of Z Z signals thus in the following figure Encoder 3 has no Z signal The WBK17 can receive input from up to four encoders however the WaveView data acquisition program can accept input from only one or two encoders To receive input from three or four encoders with one WBK17 refer to the Programmer s Manual p n 1008 0901 15 VDC 5 VDC Encoder Power Power Out Terminal Block 15 VDC E GND Encoder 3 Counter Input Terminal Blocks Encoder 2 Encoder 1 WBK17 Partial Three Encoders with Single Ended Connections to WBK1I7 Connect three encoders to the WBK17 as shown in the table below Each signal A B can be connected as a single ended connection with respect to the common ground or as a true differential input All three encoders can draw their power from the power output connector Connect the encoder s power input to the 5V or 15V power connect the return to COM on the same connector Make sure that the current outp
12. eliminates switch induced transients typically associated with electro mechanical devices including relays proximity switches and encoders From the following illustration we can see that there are two debounce modes as well as a debounce bypass In addition the signal from the comparator can be inverted before it enters the debounce circuitry The inverter is used to make the input rising edge or falling edge sensitive Edge selection is available with or without debounce In this case the debounce time setting is ignored and the input signal goes straight from the inverter or inverter bypass to the counter module There are 16 different debounce times In either debounce mode the debounce time selected determines how fast the signal can change and still be recognized The two debounce modes are trigger after stable and trigger before stable A discussion of the two modes follows Inverter Bypass Debounce Bypass From Comparator To Counters Inverter Debounce Model WBK17 Counter Encoder Module 987996 WBK17 pg 7 Trigger After Stable Mode In the Trigger After Stable mode the output of the debounce module will not change state until a period of stability has been achieved This means that the input has an edge and then must be stable for a period of time equal to the debounce time Input Output T1 T2 T3 T4 T5 Debounce Module Trigger After Stable Mode The following time periods T1
13. from 12 5V to 12 5V in 100mV steps referred to input Since the counter output and analog waveform can be scanned together the effects of different comparator switching thresholds can be easily observed This allows easy adjustment of the comparator switching threshold based on input waveform characteristics such as noise and ringing The following diagram shows two common input waveforms a square wave that has some ringing and a sine wave The comparator threshold should be set so that the ringing on the square wave does not cause extraneous switching of the comparator causing false counts to be measured Ideally the comparator threshold should be set so that the comparator switches at the point of fastest slew rate on the input waveform This occurs in the grayed regions of the waveforms Amplitude modulated noise may also cause false switching of the comparator The effects of amplitude modulated noise can be minimized by setting the threshold at the point of fastest slew rate on the input waveform The sine wave shown below has its fastest slew rate within the gray region Set the comparator threshold within the gray regions to avoid the effects of ringing and noise Set the threshold within the gray region Setting the Comparator Threshold 987996 WBK17 Counter Encoder Module Debounce Module Each channel s comparator output can be debounced with 16 programmable debounce times from 500 ns to 25 5 ms The debounce module
14. need to go unused The WBK17 has the ability to measure the pulsewidth of an input and the time between any two edges on any two inputs The time ranges are similar to those shown for period mode except that averaging is not available The ranges given below reflect this Lower 16 bits of the 32 bit Counter Range S Ticksize nS Averaging Option l 20000 Im 100m 2000 Pulsewidth and Time Ranges for a 16 bit Value Sampling error is less than 0 2 Full 32 bit Counter lt 1 ppm Range S Ticksize nS Averaging Option WBK17 Counter Encoder Module Timing Mode This mode provides a means of measuring time between two subsequent events 1 e the edge of one channel with respect to the edge of another channel The edge selection is done in each channel s debounce setup Whenever the time measurement is latched from the counter the counter is immediately cleared and enabled for accepting the subsequent time period which starts with the next edge on the main channel Low Word High Word Increment Channel Input 20 nz 200ne 2000 ns 20000 ns To Werehooks16 Post Debource Gale All s Channel Inputs Post Debounce Mapped Cl l Alls Detection mignals Timing Mode An Example of Timing Mode The following example represents one channel in timing mode The time desired is between the rising edge on the input channel and the falling edge on the mapped channel Zeroes are returned in the
15. of alternating opaque and transparent windows through which an LED will shine There is one LED for each of the concentric circular patterns and likewise one phototransistor One phototransistor produces the A signal another phototransistor produces the B signal and the last phototransistor produces the Z signal The concentric pattern for A has 512 window pairs or 1024 4096 etc The concentric pattern for B has the same number of window pairs as A except that the entire pattern is rotated by 1 4 of a window pair Thus the B signal will always be 90 degrees out of phase from the A signal The A and B signals will pulse 512 times or 1024 4096 etc per complete rotation of the encoder The concentric pattern for the Z signal has only one transparent window and therefore pulses only once per complete rotation Representative signals are shown in the figure below Representation of Quadrature Encoder Outputs A B and Z 987996 WBK17 Counter Encoder Module As the encoder rotates the A or B signal is indicative of the distance the encoder has traveled The frequency of A or B indicates the velocity of rotation of the encoder If the Z signal is used to zero a counter that is clocked by A then that counter will give the number of pulses the encoder has rotated from its reference The Z signal is a reference marker for the encoder It should be noted that when the encoder is rotating clockwise as viewed from the back A will lead B and w
16. so the acquired data may only show every 10th count or every 100th count or whatever If the counter input is sufficiently fast and the scan period much slower a detection setpoint could be completely stepped over and go unrecognized even though the counter clearly ran through the setpoint Application Example 1 Determining how many times an encoder goes beyond a certain position A user wants to know the number of times an encoder goes beyond a certain position We will refer to the position to be exceeded as Low Limit To find the answer he completes the following steps 1 Sets a detection setpoint on Channel 1 of the WBK17 channel 9 in the scan The detection setpoint will be CH1 data gt Low Limit where Low Limit is a 16 bit value 2 Sets channel 9 in the scan to be in Encoder Mode Note that channel 9 is A channel 10 is B and channel 11 is Z 3 Sets channel 12 to count the mapped channel 4 Sets the mapped channel to Detect1 5 Starts the acquisition In this example the setpoint criteria is simple Ch1 data gt Low Limit Because of the criteria whenever the data on channel 1 goes beyond the value of Low Limit Detect1 will go high Note Detection setpoints are evaluated on a per sample basis for every scan Since each channel can have up to 16 different setpoints the WBK17 must cycle through 16 setpoints searching for a match every microsecond The first match that is found terminates the search for that c
17. through T5 pertain to the above drawing In Trigger After Stable mode the input signal to the debounce module is required to have a period of stability after an incoming edge in order for that edge to be accepted passed through to the counter module The debounce time for this example is equal to T2 and TS T1 Inthe example above the input signal goes high at the beginning of time period T1 but never stays high for a period of time equal to the debounce time setting equal to T2 for this example T2 At the end of time period T2 the input signal has transitioned high and stayed there for the required amount of time therefore the output transitions high If the Input signal never stabilized in the high state long enough no transition would have appeared on the output and the entire disturbance on the input would have been rejected T3 During time period T3 the input signal remained steady No change in output is seen T4 During time period T4 the input signal has more disturbances and does not stabilize in any state long enough No change in the output is seen T5 At the end of time period T5 the input signal has transitioned low and stayed there for the required amount of time therefore the output goes low WBK17 pg 8 987996 WBK17 Counter Encoder Module Trigger Before Stable Mode In the Trigger Before Stable mode the output of the debounce module immediately changes state but will not change state a
18. Module Four Encoders Example Setup Channel Programming Setup Encoder1 A Encoder Mode 1X option 16 bit counter Latch on SOS Encoder1 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 20000ns Encoder2 A Encoder Mode 2X option 16 bit counter Latch on SOS Encoder2 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 2000ns Encoder3 A Encoder Mode 4X option 16 bit counter Latch on SOS Encoder3 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 200ns Encoder4 A Encoder Mode 4X option 16 bit counter Latch on SOS Encoder4 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 200ns With the encoders connected in this manner there is no relative positioning information available since there is no Z signal connection Therefore only distance traveled can be measured on the A channels This means that for each encoder we can only know distance traveled and velocity of travel Setpoints can be done just like in the previous example The digital output port can be updated by any individual channel a set of selected channels or by all channels Digital Inputs The WBK17 has 16 general purpose digital inputs that can be scanned into an acquisition along with any other channel on the WaveBook system These are available on the 25 pin DSUB connector Digital Inputs Tr
19. WBK17 Counter Input Module with Quadrature Encoder Support For use with WaveBook 516 512A 516A and 516E Description 1 Hardware Setup 3 Configuration 3 Power 3 Using Fastener Panels to Stack Modules 4 Functional Concepts 4 Input Coupling 4 Analog Filtering 5 Comparator 6 Debounce Module T Terms Applicable to Counter Modes 11 Counter Options 11 Counter Totalize Mode 12 Period Mode 14 Pulsewidth Mode 17 Timing Mode 19 Encoder Mode 20 Digital Inputs 29 Digital Outputs 30 Pattern Detection and Data Markers 31 Software Support 31 Fuse Replacement 36 WBK17 Specifications 37 Description COUNTER INPUT _ r POWER OUT IN DIGITAL EXPANSION OUT 3 3 ee ACTIVE Front Panel i wll ne 4 eee COMLH LH COMLH LH COMLH LH COMLH LH COM COM DIG IN TRG CLK WBK17 CHi CH2 CH3 CH4 CH5 CH6 CH7 CH8 5 15 MADE IN U S A COUNTER ENCODER MODULE ieee EPD a Vitis Caia Rear Panel Se SE iir Mamie E OCJo oC jo CC LO POWER IN POWER OUT EXPANSION EXPANSION gt c ani USA i ac TONOS vem DIGITAL OUTPUTS CONTROL IN CONTROL OUT Bice Che Signa arc E WBK17 Modules Showing Front and Rear Panels Front Panel Counter Input snap in terminal blocks Includes connections for Common Low amp High for each of 8 channels Power Out
20. WBK17 is supported by a complete set of language drivers and documentation for developing custom applications using high level languages such as Visual Basic C and Delphi for Windows 95 98 2000 Me NT and LabVIEW For applications that require sophisticated graphical analysis and control that go beyond the scope of WaveView icon based DASYLab software can be used The WaveBook User s Manual p n 489 0901 discusses software options WBK17 support is only available with the 32 bit driver and 32 bit version of WaveView Reference Notes gt For information regarding software installation refer to the WaveBook User s Manual p n 489 0901 gt For detailed information regarding WaveView refer to the WaveView document module included as a part of the WaveBook User s Manual gt If creating custom programs refer to the Programmer s Manual p n 1008 0901 WBK17 Counter Encoder Module 987996 WBK17 pg 35 Fuse Replacement The WBK17 has three user replaceable fuses as follows FI Power Output Fuse for 15V Encoder Power 1 0 A Mini ATO Located near the center of the front panel see figure F2 Power Output Fuse for 5V Encoder Power 2 0 A Mini ATO Located near the center of the front panel see figure e F201 Input Power Fuse 4 0 A Mini ATO Located between the SDIN Power In connector and the DC DC Converter see figure WARNING Electric shock hazard Remove the WBK17
21. WaveBook User s Manual p n 489 0901 provides tables for calculating system power requirements and discusses power supply options gt Encoder wiring diagrams are included in the Encoder section of functional concepts These drawings begin on page 23 CE Kit If your WBK17 is to be part of a CE compliant system you will need to use part number WBK17 CE KIT The kit includes the terminal block headers and cable housings that are needed to cover exposed sections of connectors and wiring thus bringing your WBK17 up to meet or exceed CE standards For a list of applicable CE Safety and EMC standards as well as the CE Compliant Operating Conditions that have been specified for WBK17 refer to the WBK17 Declaration of Conformity p n 1064 0740 WBK17 Counter Encoder Module 987996 WBK17 pg 3 Using Fastener Panels to Stack Modules For convenient mounting the WBK17 has the same footprint as other WBK modules and WaveBooks Fastener Panels sometimes referred to as splice plates provide a means of stacking WaveBooks and modules Optional screw on handles are available for portable applications Refer to this manual s introduction for assembly information When using WBK17 modules in conjunction with other WBK modules the WBK17 modules must be located closest to the WaveBook due to the CA 217 cable length The order of the other WBK modules does not matter Fastener panels will partially block the vents on WBK16s and the v
22. a digital output port update with mask CE Compliance 987996 In regard to CE Compliance refer to the WBK17 Declaration of Conformity p n 1064 0740 As stated in that document one of the several requirements for CE compliance is the use of a WBK17 CE kit p n WBK17 CE Kit Contact the factory or your service representative should you desire detailed information The Declaration of Conformity is shipped with the WBK17 module WBK17 pg 37 Note WBK17 pg 38 987996 WBK17 Counter Encoder Module
23. account when setting the comparator threshold Many times the best way to accommodate unbalanced inputs is to AC couple and set the threshold at 0 00V This forces the comparator to trigger on the center of the waveform where the input has high slew and little noise An option is to DC couple and set the comparator threshold at the mid point of the transition If external pullup resistors are required they can be connected at the WBK17 s input terminal blocks A pullup resistor can be placed between any input channel and one of the two power supplies offered on the output power connector 5V and 15V Choose a pullup resistor value based on the encoder s output drive capability and the input impedance of the WBK17 Lower values of pullup resistors will cause less distortion but also cause the encoder s output driver to pull down with more current Although the WBK17 has a wide input dynamic range and good common mode rejection you should connect the encoder GND to the COM input when possible Analog Filtering Bypass 100 kHz Frat Coupling Stage To Comparator 30 Hz Analog Filter Each channel has a single pole low pass filter with three programmable cut off frequencies These are 100 kHz 20 kHz and 30 Hz Use analog filtering to reject low level noise that may otherwise interfere with the comparator The analog filters are most beneficial when the unwanted noise is far outside the desired bandwidth
24. bit mask byte and a control byte can be assigned to a channel When a set point has been programmed count value period pulsewidth position or velocity the two 16 bit values are compared in real time to the measured value for that channel When the comparison condition is met the output port is updated instantaneously Valid conditions include greater than value less than value inside the window and outside the window Since each set point has an 8 bit mask byte any or all of the digital output bits can be updated With 16 setpoints per channel complex updating schemes can be defined to meet the most demanding application requirements WBK17 pg 30 987996 WBK17 Counter Encoder Module Pattern Detection and Data Markers The WBK17 has a pattern detection feature that can be individually programmed for any of the 8 input channels The pattern detection feature allows up to 16 detection setpoints to be set on each channel Each detection setpoint can be programmed in several ways inside the window outside the window above setpoint below setpoint When a channel s setpoint criteria has been met a digital marker signal called the detect signal will go high The detect signals can also be part of the scan group and measured just like any other input channel allowing real time data analysis during an acquisition Each setpoint can also update the digital output port with a data byte and mask byte allowing real time control based on acquisi
25. counter With this option the input channel for the counter will increment the counter The mapped channel can be used to decrement the counter COUNTER OPT6 Allows the mapped channel to increment the counter instead of the main channel This option allows the counter to be used with any other input channel post debounce or with one of the detection signals If the channel s input is used elsewhere for example gating another counter the counter for this channel does not need to go unused Reference Notes For information on implementing Up Down Counters of any size refer to Application Example 2 on page 26 of this document module WBK17 Counter Encoder Module 987996 WBK17 pg 13 Period Mode WBK17 pg 14 This mode allows for period measurement of the channel input The measurement period is the time from edge to edge either both rising or both falling Period data is latched as it becomes available and the data is sent to the WaveBook at the scan rate Therefore if the scan period is much faster than the input waveform there will be a great deal of repetition in the period values This repetition is due to the fact that updates take place only when another full period becomes available Low Word High Word Incrernent Channel Input 20 ng 200 ns 2000 ns 20000 ns Post Debounce OPT6 To Wavebooks14A Kapped Channel Alls Channel Inputs Post Debournce AS Detection mignials Period
26. d therefore any edge on the input after time period T6 will be immediately reflected in the output of the debounce module Mode Comparison The following example shows how the two modes interpret the same input signal which exhibits glitches Notice that the Trigger Before Stable mode will recognize more glitches than the Trigger After Stable mode Use the bypass option to achieve maximum glitch recognition Debounce i Debounce Debounce Time Time Time I 1 3 i l Input Trigger Before Stable Trigger After Stable o Example of Two Debounce Modes Interpreting the Same Signal WBK17 Counter Encoder Module 987996 WBK17 pg 9 WBK17 pg 10 Debounce times should be set according to the amount of instability expected in the input signal Setting a debounce time that is too short may result in unwanted glitches clocking the counter Setting a debounce time too long may result in an input signal being rejected entirely Some experimentation may be required to find the appropriate debounce time for a particular application To see the effects of different debounce time settings simply view the analog waveform along with the counter output Use trigger before stable mode when the input signal has groups of glitches and each group is to be counted as one The trigger before stable mode will recognize and count the first glitch within a group but reject the subsequent
27. ds of the input channel 3 The number returned is 100 consecutive periods 4 The number returned is 1000 consecutive periods PERIOD OPT2 Determines whether the period is to be measured with a 16 bit Counter Low or 32 bit Counter High counter Since period measurements always have the stop at the top option enabled this option dictates whether the measurement has a range of 0 to 65535 ticks or 0 to 4 294 967 295 ticks PERIOD OPT4 Allows the mapped channel to gate the counter if desired When the mapped channel is high the counter is enabled When the mapped channel is low the counter is disabled but still holds the count value The mapped channel can be any other input channel or a detection signal 987996 WBK17 Counter Encoder Module PERIOD OPT6 This allows a mapped channel s period to be measured instead of the input channel The mapped channel can be any other input channel post debounce or one of the detection signals on any channel This option allows the counter to be used with any other input channel post debounce or with one of the detection signals If the channel s input is used elsewhere for example gating another counter the counter for this channel does not need to go unused Period and Frequency Accuracy The WBK17 can measure the period of any input waveform It does this by counting the integral number of ticks that make up the period the data returned will always be time measured
28. e increment the counter e decrement the counter The mapped channel can be any of the eight input channels post debounce or any of the eight detection signals Each channel has its own detection signal that goes active when any of the sixteen counter value setpoints has been reached A detailed explanation of pattern detection begins on page 31 of this document module Low Word Channel Input High Word Fost Debource To Weavebooko16 start OF Scan Signal All Channel Inputs Post Debounce AS Detection mignals Counter Totalize Mode An explanation of the various counter options depicted in the previous figure follows WBK17 pg 12 987996 WBK17 Counter Encoder Module COUNTER OPT0 This selects totalize or clear on read mode Totalize Mode The counter counts up and rolls over on the 16 bit Low Counter boundary or on the 32 bit High Counter boundary See OPT2 in regard to choosing 16 bit or 32 bit counters Clear On Read Mode In WaveView the Clear On Read Mode is referred to as the Counter mode The counter is cleared at the beginning of every scan and the final value of the counter the value just before it was cleared is latched and returned to the WaveBook When using either an EXT CLK input or one or both SYNC ports the clear on read mode is not available In these instances the totalize mode should be used COUNTER OPTI This determines if the counter is to rollover o
29. e page 19 OPT2 Determines whether the time is to be measured with a 16 bit counter Counter Low or a 32 bit counter Counter High Encoder Mode see page 20 OPT 1 0 Determines the encoder measurement mode 1X 2X or 4X OPT2 Determines whether the counter is 16 bits Counter Low or 32 bits Counter High OPT3 Determines which signal latches the counter outputs into the data stream going back to the WaveBook Start of scan or mapped channel OPT4 Allows the mapped channel to gate the counter OPTS Allows the mapped channel to clear the counter for Z reference Counter Totalize Mode The counter mode allows basic use of a 32 bit counter While in this mode the channel s input can only increment the counter upward When used as a 16 bit counter Counter Low one channel can be scanned at the 1MHz rate When used as a 32 bit counter Counter High two sample times are used to return the full 32 bit result Therefore a 32 bit counter can only be sampled at a 500kHz maximum rate If only the upper 16 bits of a 32 bit counter are desired then that upper word can be acquired at the 1MHz rate The first scan of an acquisition always zeroes all counters It 1s usual for all counter outputs to be latched at the beginning of each scan however there is an option to change this A second channel referred to as the mapped channel can be used to latch the counter output The mapped channel can also be used to e gate the counter
30. ents on WaveBook 512A 516 516A and 516E when the units are stacked This partial blocking of vents does not jeopardize the cooling process Functional Concepts Input Coupling WBK17 pg 4 Each WBK17 channel has a programmable input coupling feature Input coupling can be turned off or be selected for AC or DC coupling The type of coupling is determined after the input differential amplifier DC coupling makes use of the path going straight to the filter stage of the programmable analog filter where as AC coupling makes use of the path with the 1 uF capacitor The inclusion or exclusion of DC offsets is important when calculating the appropriate comparator threshold for the input waveform Use AC coupling to reject unwanted DC offsets In other words to prevent DC offsets from reaching the comparator AC coupling works well when the input is constantly changing If the input stops for longer than one second it will appear as DC and may cause the comparator to switch on the decaying DC input Use DC coupling when both AC and DC components are to be presented as input to the comparator DC coupling does not reject anything If the input can have periods of stability longer than one second use DC coupling so the comparator does not switch on a decaying DC input 4 kfl Channel Input DC Coupling To Filter Channel Input Stage Differential Amplifier l uF 20 kE AC Coupling 100 ke2 Input C
31. er Encoder Module 987996 WBK17 pg 25 Application Example 2 Using Encoder mode to implement Up Down Counters of any size The encoder mode does not have to be used exclusively with quadrature encoders The encoder mode can be used to implement a 16 or 32 bit counter that has direction control The encoder mode can also be used to force the counter to rollover on any value When an odd numbered channel 1 3 5 7 is put in encoder mode the next higher channel 2 4 6 8 is automatically selected to be the direction control Therefore if channel 1 is in encoder mode channel 2 is the direction control Channel 1 s counter will count up at the edge rate coming in on channel 1 if channel 2 is low and channel will count down if channel 2 is high If channel 1 s counter is required to decrement only then channel 2 can be forced high by software set the coupling mode to OFF and the comparator threshold to negative 12V Any input channel can be forced to a low or high simply by setting the coupling mode to OFF and setting the appropriate threshold level When a channel is turned OFF the input settles to 0 0V setting a positive threshold will force a low and setting a negative threshold will force a high Encoder mode allows the mapped channel to clear the counter If the mapped channel is programmed to be the detection signal for the counter then the counter will rollover to zero when the setpoint criteria is met The setpoint criteria c
32. er Options The following mode options are available with the WBK17 and are detailed in the upcoming pages A separate block diagram has been created for each mode Note that the OPT numbers relate to sections of the block diagrams Counter Totalize Mode see page 12 OPTO Selects totalize or clear on read mode OPT1 Determines if the counter is to rollover or stop at the top OPT2 Determines whether the counter is 16 bits Counter Low or 32 bits Counter High OPT3 Determines which signal latches the counter outputs into the data stream back to the WaveBook Start of scan or mapped channel OPT4 Allows the mapped channel to gate the counter OPT5 Allows the mapped channel to decrement the counter OPT6 Allows the mapped channel to increment the counter Period Mode see page 14 OPT 1 0 Determines the number of periods to time per measurement 1 10 100 1000 OPT2 Determines whether the period is to be measured with a 16 bit Counter Low or 32 bit Counter High OPT4 Allows the mapped channel to gate the counter OPT6 Allows the mapped channel to be measured for periods Pulsewidth Mode sce page 17 OPT2 Determines whether the pulsewidth is to be measured with a 16 bit counter Counter Low or a 32 bit counter Counter High OPT4 Allows the mapped channel to gate the counter OPT6 Allows the mapped channel to be measured for pulsewidth WBK17 Counter Encoder Module 987996 WBK17 pg 11 Timing Mode se
33. er option is to have the mapped signal latch the counter outputs This allows the user to have another signal control the latching of the count data so the exact value of the counter is known when an edge is present on another channel ENCODER OPT4 This allows the mapped channel to gate the counter if desired When the mapped channel is high the counter is enabled to count when the mapped channel is low the counter is disabled but holds the count value The mapped channel can be any other input channel or one of the detection signals ENCODER OPT5 This allows the mapped channel to clear the counter if desired OPTS implements the Z function described above allowing the encoder reference to clear the counter The counter is cleared on the rising edge of the mapped channel WBK17 Counter Encoder Module 987996 WBK17 pg 21 Encoder Wiring Diagrams You can use up to four encoders with each WBK17 module in your WaveBook system Each A and B signal can be made as a single ended connection with respect to common ground or as a differential connection Encoder wiring diagrams and example setup tables are included in the following pages refer to them as needed For Single ended Connections For single ended applications the connections made from the encoder to WBK17 s front panel are as follows e Signals A B and Z connect to the H channel high connectors on WBK17 s Counter Input Terminal Blocks A B and Z highs
34. gain until a period of stability has passed For this reason the mode can be used to detect glitches Debounce Module Trigger Before Stable Mode The following time periods T1 through T6 pertain to the above drawing T1 In the illustrated example the Input signal is low for the debounce time equal to T1 therefore when the input edge arrives at the end of time period T1 it is accepted and the Output of the debounce module goes high Note that a period of stability must precede the edge in order for the edge to be accepted T2 During time period T2 the input signal is not stable for a length of time equal to T1 the debounce time setting for this example Therefore the output stays high and does not change state during time period T2 T3 During time period T3 the input signal is stable for a time period equal to T1 meeting the debounce requirement The output is held at the high state This is the same state as the input T4 At anytime during time period T4 the input can change state When this happens the output will also change state At the end of time period T4 the input changes state going low and the output follows this action by going low T5 During time period T5 the input signal again has disturbances that cause the input to not meet the debounce time requirement The output does not change state T6 After time period T6 the input signal has been stable for the debounce time an
35. ge tables below Sampling error can also be reduced by averaging many samples together Assuming the input signal is asynchronous to the WBK17 s internal timebase sampling error can be divided by the square root of the number of samples taken The averaging can be done with PC based software The WBK17 has the ability to measure 1 10 100 or 1000 periods dividing the sampling error by 1 10 100 or 1000 This is done inside the WBK17 and may eliminate the need for any averaging to be done in the PC For high accuracy on high frequency inputs multiple period measurement and PC based averaging can be done The WBK17 has the ability to provide various frequency ranges that are based upon different ticksizes averaging options and counter size 16 bit or 32 bit values The frequency ranges are designed to fit a wide array of possible applications Within each range the sampling error decreases dramatically as the input period increases The ranges will get smaller as required accuracy increases Upper 16 bits of the 32 bit counter Lower 16 bits of the 32 bit counter Range Hz Ticksize Averaging Range Hz Ticksize nS Averaging nS Option Option 15u 1500u 20000 1 100 20000 150u 15m 2000 10 1k 2000 Frequency Ranges for a 16 bit value sampling error is less than 0 2 WBK17 Counter Encoder Module 987996 WBK17 pg 15 WBK17 pg 16 Each frequency range given in the previous table set can be exceded If t
36. glitches within the group if the debounce time is set accordingly The debounce time should be set to encompass one entire group of glitches as shown in the following diagram Debounce Time I I Input E LLU LLL Trigger Before Stable l Trigger After Stable Trigger after stable mode behaves more like a traditional debounce function rejecting glitches and only passing state transitions after a required period of stability Trigger after stable mode is used with electro mechanical devices like encoders and mechanical switches to reject switch bounce and disturbances due to a vibrating encoder that is not otherwise moving The debounce time should be set short enough to accept the desired input pulse but longer than the period of the undesired disturbance as shown in the diagram below Debounce Time i i Trigger Before Stable l Trigger After Stable 987996 WBK17 Counter Encoder Module Terms Applicable to Counter Modes The following terms and definitions are provided as an aid to understanding counter modes Detection Signal A detection signal is one of 8 outputs of the pattern detection module Each input channel has an associated detection signal Detect 1 for Channel 1 Detect 2 for Channel 2 etc A channel s detection signal will go active high when that channel s counter value meets the setpoint criteria programmed into the pattern detection module Detection signals can be scanned along with any o
37. hannel s current sample Once the match has been found the digital output port can be updated or NOT and the Detect1 signal for channel 1 will be taken high The following timing diagram represents detection setpoints being used to drive a Detection signal for channel 1 Detectl for Channel 1 Channel 9 in the scan PPE PEPE a Timing Diagram with Channel Detection Signal As shown in the diagram Detect1 for Channel 1 Channel 9 will go high for those samples that meet the setpoint criteria Ch1 data gt Low Limit Note that the Detect signal can get routed to another counter channel and be used at that channel to clock a counter This allows the user to count the number of times an encoder crosses a specified boundary As an alternative the Detect signal s pulsewidth could be measured giving the amount of time that the encoder spent beyond the setpoint criteria The channel s data stream will return data indicative of the time that Detect was active high and more importantly the time that the encoder s position was within the setpoint window Keep in mind that the timing resolution of the Detect signal is directly related to the Scan period not to the actual counter Therefore smaller scan periods result in better timing resolution for the Detect signal and for measurements based on the Detect signal Tr Having your Detect signal as a part of the scan group allows for real time data analysis WBK17 Count
38. he input waveform goes under range by too much the counter value will top out at 65535 indicating you have reached the lowest possible frequency that can be measured on that range If the input waveform goes over range by too much the counter will return values that are very course and have a lot of sampling error The values returned will have a small number of counts for the period duration If an input waveform cannot fit within one of the 16 bit ranges shown above or requires much higher accuracy then a 32 bit range should be considered Full 32 bit Counter Option 15u 100 20000 ELES 15 5M Frequency Ranges for a 32 bit Value Sampling Error is Less than 0 2 The 32 bit ranges shown above are much wider than the 16 bit ranges but also require the full 32 bit value to be returned this requires two sample periods within each scan group The 32 bit frequency ranges can also be exceeded with a loss of accuracy or topping out at 4 294 967 295 counts Some measurements will require the accuracy of an input waveform to be free of sampling error having only the absolute accuracy of the internal timebase as the source of error Sampling error can be averaged out to give the required result In most cases the WBK17 can perform the required averaging on the values before they are returned to the PC The frequency ranges shown below will give a sampling error that is less than 10ppm or 1ppm Full 32 bit Counter lt 10 ppm Range H
39. hen the encoder is rotating counter clockwise A will lag B Ifthe counter direction control logic is such that the counter counts upward when A leads B and counts downward when A lags B then the counter will give direction control as well as distance from the reference An Example of Encoder Accuracy If there are 512 pulses on A then the encoder position is accurate to within 360 degrees 512 Even greater accuracy can be obtained by counting not only rising edges on A but also falling edges on A giving position accuracy to 360 degrees 1024 The ultimate accuracy is obtained by counting rising and falling edges on A and on B since B also has 512 pulses This gives a position accuracy of 360 degrees 2048 These 3 different modes are known as 1X 2X and 4X The WBK17 implements all of these modes and functions as described in the following options OPT4 Low Word High Word Channels 1 3 4 7 Post Debounce 32 Bits Increment Channels 2 4 6 8 Post Debource To Wavebook16 ANE Channel Inputs Start of scan Signal Post Debounce Mapped Channel Alls Detection mignials Encoder Mode ENCODER OPT 1 0 This determines the encoder measurement mode 1X 2X or 4X ENCODER OPT3 This determines which signal latches the counter outputs into the data stream going back to the WaveBook Normally the start of scan signal latches the counter outputs at the beginning of every scan The oth
40. idth Mode An example one channel s acquired data might be 0 0 0 0 80 80 80 80 79 79 79 79 81 81 81 81 This data represents the number of ticksize intervals counted during the pulsewidth measurement The first value s returned will be zero since the counters are cleared at the beginning of the acquisition In this example the data comes in sets of four because the scan period is about one fourth as long as the input channel s period Every time the pulsewidth measurement is latched from the counter the counter is immediately cleared and enabled to count time for the next pulsewidth If the scan period is much slower than the input period then the acquisitions will miss some pulsewidths Decreasing the scan period will increase the number of different pulsewidths received The data returned is interpreted as time measured in ticks There are four timebase settings 20 ns 200 ns 2 us and 20 us These are often referred to as tick sizes The WBK17 uses a 50 MHz 10 ppm oscillator as a timing source If the input signal has a poor slew rate the pulsewidth mode will provide variant results dependant upon the comparator threshold PULSEWIDTH OPT2 Determines whether the pulsewidth is to be measured with a 16 bit Counter Low or 32 bit counter High counter Since pulsewidth measurements always have the stop at the top option enabled this option dictates whether the measurement has a range of 0 to 65535 ticks or 0 to 4 294
41. igger External Clock connector located on the WBK17 front panel as shown in the figure on page 1 of this document module The following signals are present on the DB25F high speed digital I O connector e16 High Speed Digital Input Lines DO through D15 eTTL Trigger Input TTLTRG e 15 V pin 23 15 V pin 22 50 mA max each etwo 5 V pin 19 and pin 21 250 mA max total eExternal Clock pin 20 etwo Digital Grounds pins 24 and 25 To sample just 16 digital input signals connect them directly to the digital Input data lines D15 is the most significant bit and DO is the least The following figure depicts WBK17 s DB25 connector rotated 90 degrees counter clockwise for convenience of labeling Note that an optional Clock and External Trigger cable CA 178 is available for use with the WBK17 The cable connects to the DB25 connector and terminates in two BNC connectors one for an external clock via pin 20 and the other to TTL external trigger via pin 13 Digital I O Connections for WBK17 Ho a ool D9 D0 D15 High Speed Digital Input data lines a e l D10 TTLTRG TTL trigger input D2 4 l External Clock 16 bit mode read write strobe I i l NC 5 VDC 250 mA maximum D 7e 5 V 15 15 VDC 50 mA maximum each D 8 I A D7 oea D13 10470 3 D14 11 I DiS 12470 J TILTRG 13 External Clock f Digital Grounds Pins 24 and 25 E 15 VDC ae 15 VDC WBK17
42. in ticks The error in each data sample will come from two sources the sampling error caused by not being able to count a partial tick and the WBK17 s internal timebase inaccuracy The WBK17 s internal timebase has an absolute accuracy of 10ppm The sampling error will vary with input frequency selected ticksize and selected averaging mode The absolute error is the root sum of squares of the two independent error sources For example if the sampling error is 10ppm and the timebase accuracy is 10ppm the absolute accuracy 1s 14 1 ppm Many times the desired accuracy is much less than what the internal timebase is capable of Other applications will require a more accurate period measurement and the effects of sampling error will have to be averaged out leaving only the inaccuracy associated with the internal timebase Inaccuracy due to the internal timebase cannot be averaged out For period and frequency measurements percent sampling error is equal to 100 n 1 where n 0 to 65 535 for a 16 bit counter and n 0 to 4 294 967 295 for a 32 bit counter For small count values the sampling error is large and for large count values the sampling error is small If sampling error is to be less than 0 2 n must be greater than 499 regardless of counter size If sampling error is to be less than 0 001 10 ppm n must be greater than 99 999 which requires use of a 32 bit counter These values of n were used to derive the frequency ran
43. inning on page 3lof this document module A typical acquisition might take 6 readings off of the WBK17 module as illustrated below The user determines the scan rate and the number of scans to take Note that the channel numbers shown assume that the WBK17 is the first expansion module car l acar ocan 3 ps fp WBK17 Acquisition of Six Readings per Scan In general the output of each channel s counter is latched at the beginning of each scan period called the start of scan Every time the WBK17 receives a start of scan signal from the WaveBook the counter values are latched and are available to be sourced down to the WaveBook as each WBK17 channel is selected during the scan period The WBK17 clears all counter channels at the beginning of the acquisition This means that the values returned during scan period will always be zero The values returned during scan period 2 reflect what happened during scan period 1 The scan period defines the timing resolution for the WaveBook and the WBK17 If you need a higher timing resolution shorten the scan period 987996 WBK17 Counter Encoder Module If more timing resolution is needed the scan period must be shortened This has an impact when setting a detection setpoint because the values coming back from the acquisition have the timing granularity defined by the scan period not the actual counter The counter may be counting very fast but the scan period could be much slower
44. mit 1 Logical E t Detect 1 oe Example Detection Channel 1 in Totalizing Counter Mode l L L L I aR E E E E A E A ee eee ee ENEE EEE L l L L l te E st E E E A Sa mee The detection circuit works on data that is latched out of the counters and put into the acquisition stream at the scan rate This data is acquired according to the pre acquisition setup scan group scan period etc and returned to the PC The actual counters may be counting much faster than the scan rate and therefore only every 10 100 or n count will show up in the acquisition data Therefore it is possible to set a small detection window on a totalizing counter channel and have the detection setpoint stepped over since the scan period was too long Even though the counter value stepped into and out of the detection window the actual values going back to the PC may not This is true no matter what mode the counter channel is in The setting of a detection window must be done with a scan period in mind Two possible solutions for overcoming this problem The scan period could be shortened to give more timing resolution on the counter values or the setpoint window High Limit and Low Limit could be widened Perhaps a combination of both solutions is the best compromise Example Setpoint Detection on Encoder Position and Velocity The figure below shows how setpoints can be used on two channels Channel 4 is in encoder mode u
45. nal A B Z can be connected as a single ended connection with respect to the common ground or as a true differential input Both encoders can draw their power from the WBK17 s power output connector Connect the encoder s power input to the 5V or 15V power connect the return to common ground COM on the same connector The programming setup given below is just a representative of possible options Two Encoders Example Setup Example Programming Setup Encoder1 A Encoder Mode 4X option 16 bit counter Latch on SOS Map channel Clears the counter set Map channel to 3 Encoder1 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 200ns Encoder1 Z Counter in Totalize mode stop at the top 16 bit counter No connection Encoder2 A Encoder2 B Encoder2 Z WBK17 Counter Encoder Module 987996 WBK17 pg 23 WBK17 pg 24 There are other useful encoder options for example analog filtering If the encoders are known to run in a noisy environment then some analog filtering may be in order A low pass filter with 20kHz or 100kHz cutoff frequency can be used to reduce extraneous high frequency normal mode noise that may come in on the encoder lines In addition if the encoder is connected in differential mode any common mode noise will be reduced by the common mode rejection of the WBK17 s front end differential amplifier typically 70dB If the encoder stops rota
46. nts and higher word setpoints were programmed for a channel that channel would have 32 programmed setpoints driving the detect signal during the acquisition All setpoints are programmed as part of the pre acquisition setup similar to setting up the analog path debounce mode or counter mode setup As stated above each setpoint acts on 16 bit data Therefore each setpoint has two 16 bit compare values High Limit and Low Limit The High Limit and Low Limit values define the setpoint window Each setpoint has four comparison types 1 inside the window 2 outside the window 3 greater than value and 4 less than value The programmed comparison type tells the detection module how to compare the channel s data value to the values of High Limit and Low Limit Each setpoint can also be programmed with an 8 bit digital output byte DigOut and corresponding 8 bit mask byte DigMask When the setpoint criteria has been met the digital output port can be updated with the given byte and mask The digital output port can also be part of the setpoint comparison Any setpoint can be programmed to take the detect signal high when the digital output port is equal to the 8 bit digital byte DigComp qualified by the 8 bit DigMask If any of the digital output port bits are not going to be driven as outputs they can act as inputs that drive the detection signals via setpoints The diagram below summarizes the comparisons that are possible WBK17
47. ould be a simple greater than limit forcing the counter to rollover on 1000 for example The following steps show how to set up a counter so that it will rollover on the count value of 1000 1 Configure Channel 1 as Encoder mode 1X option 16 bit counter Map channel clears the counter option set the Map channel to Detect 1 Select desired coupling low pass filtering comparator threshold and debounce 2 Configure Channel 2 as e Analog mode e Coupling OFF e LPF 30Hz e Comparator threshold 12 0V Tr If you want to observe the terminal count on pulsing high scan the Detect signals 3 Program a setpoint on channel 1 to be greater than 1000 This will take Detect 1 high whenever channel 1 s acquired counter data is greater than 1000 4 Take 10 000 scans at a scan rate of 2 kHz 5 Connect a 1kHz signal to channel 1 s input Make sure it meets the comparator threshold setting 6 Take the acquisition The counter on channel will count up and rollover on the count of 1000 Since the pattern detection circuit works on data that is latched into the data stream the scan rate must be greater than the input edge rate If the scan rate is less than the input edge rate then the counter will actually count up beyond 1000 before the count value is sampled detected and then cleared back to zero It is important to realize that the Detect signals have the timing resolution of the scan period and that the pattern
48. oupling The input coupling stage shown in the figure above is compatible with encoder outputs that have balanced outputs driving both high and low The high and low voltages are required to be within the maximum input voltage range of 75V to 75V A wide range of input waveforms can be accommodated since the WBK17 s comparator threshold can be set anywhere from 12 5V to 12 5V Many encoders offer line driver outputs using 4469 or 8830 driver circuits The 8830 is a dual differential line driver with balanced TTL outputs capable of directly driving long lengths of coax or twisted pair cable The 4469 is a 987996 WBK17 Counter Encoder Module CMOS output driver with high current outputs used with voltages of up to 15 V Balanced line drivers that are used at higher voltages e g 15 V and 24 V and used in differential mode are particularly immune to external noise sources Some encoder outputs will be open collector type These require a pullup resistor in order to operate In many cases the pullup resistor is already incorporated inside the encoder other times it must be supplied externally Since the open collector with pullup resistor output is inherently unbalanced drives strongly in the low direction weakly in the high direction the input differential amplifier will distort the input waveform This distortion can be easily viewed when the input channel is scanned by the WaveBook This distortion may have to be taken into
49. r stop at the top Rollover Mode The counter continues to count upward rolling over on the 16 bit Counter Low boundary or on the 32 bit Counter High boundary See OPT2 in regard to choosing 16 bit or 32 bit counters Stop at the Top Mode The counter will stop at the top of its count The top of the count is FFFF for the 16 bit option Counter Low and FFFFFFFF for the 32 bit option Counter High COUNTER OPT2 Determines whether the counter is 16 bits or 32 bits Counter Low or Counter High respectively This only matters when the counter is using the stop at the top option otherwise this option is inconsequential COUNTER OPT3 Determines which signal latches the counter outputs into the data stream back to the WaveBook Normally the start of scan signal latches the counter outputs at the beginning of every scan but an option is to have the mapped signal latch the counter outputs This mapped signal option allows a second signal to control the latching of the count data This allows the user to know the exact counter value when an edge is present on another channel COUNTER OPT4 Allows the mapped channel to gate the counter if desired When the mapped channel is high the counter is enabled When the mapped channel is low the counter is disabled but holds the count value The mapped channel can be any other input channel or one of the detection signals COUNTER OPT5 Allows the mapped channel to decrement the
50. r four encoders For differential connections we would simply make A B and Z signal connections to the respective channel low inputs With four encoders it should be noted that there are no channels available for Z Z signals In this scenario no encoder has a Z signal connection The WBK17 can receive input from up to four encoders however the WaveView data acquisition program can accept input from only one or two encoders To receive input from three or four encoders with one WBK17 refer to the Programmer s Manual p n 1008 0901 Encoder Power Power Out Terminal Block 15 VDC 5 VDC CH8H CH8L CH7H Encoder 4 Encoder 3 Counter Input Terminal Blocks Encoder 2 WBK17 Partial Encoder 1 Four Encoders with Single Ended Connections to WBK17 Connect four encoders to the WBK17 Refer to the above diagram and following table Four Encoders Example Setup as needed Each signal A B can be connected as a single ended connection with respect to the common ground or as a true differential input All four encoders can draw their power from the power output connector connect the encoder s power input to the 5V or 15V power connect the return to COM on the same connector Make sure that the current output spec is not violated or a fuse may blow The programming setup given below is just a representative of possible options 987996 WBK17 Counter Encoder
51. s 16 bit or 32 bit 4 time bases to choose from 20 ns 200 ns 2 us 20 us any other channel can gate the period measurement Pulsewidth Mode Options 16 bit or 32 bit values 4 time bases to choose from 20 ns 200 ns 2 us 20 us any other channel can gate the pulsewidth measurement Timing Mode Options 16 bit or 32 bit values 4 time bases to choose from 20 ns 200 ns 2 us 20 us Encoder Mode Options x1 x2 x4 options 16 bit or 32 bit values Z channel clearing of the counter any other channel can gate the counter Digital Inputs Inputs 8 Digital Inputs Connector DB25 female Configuration 16TTL compatible pins Input Characteristics TTL compatible Input Output Protection Diode clamped to ground and to 5V Digital Outputs Outputs 8 Digital Outputs Connector Removable screw terminal block Output Type Open drain DMOSFET Output Pullup Resistor 27k Ohm to 5V Output Sink Current 150 mA output continuous 500 mA output peak lt 100 us 150 total continuous per bank of 8 outputs Output Voltage Range 0 to 5V no external pullup required 0 to 30V with external pullup resistor Output Resistance 10 Ohms maximum Note All digital outputs are fully programmable with masking Detection Circuit Digital Pattern Detection Choices Greater than value less than value inside the window outside the window Detection Setpoints Per Channel 16 Note that each detection setpoint can be associated with
52. s for WBK17 applications begin on page 22 of this document module gt Refer to the WaveBook User s Manual p n 489 0901 in regard to power expansion control and expansion signal connections gt When using WaveView you will need to set several parameters so WaveView can best meet your application requirements For software information refer to the WaveBook User s Manual p n 489 0901 Power Power In to the WBK17 The WBK17 can be powered by an included AC power adapter or from any 10 to 30 VDC source such as a car battery Check the WBK17 specifications for current requirements For portable or field applications the WBK17 and the WaveBook can be powered by the DBK30A Battery Module or the DBK34 UPS Battery Module Both devices contain rechargeable battery packs The WaveBook User s Manual p n 489 0901 includes details Power Out io the Encoders The WBK17 provides output power of 5V at 1A and 15V at 500 mA to supply power to encoders Power connections from the WBK17 to up to 4 encoders are made on the snap in screw terminal block located on the WBK17 s front panel Example wiring diagrams for encoders begin on page 23 You must compute power consumption for your entire system You may need to use auxiliary or high current power supplies The WaveBook User s Manual p n 489 0901 includes tables for calculating system power requirements and discusses power supply options Reference Notes gt The
53. scan until one complete time measurement has been taken At that point the value time in ticks is latched and output to the WaveBook until the next time measurement has been completed Rising edges on the input channel will clear the counter and falling edges on the mapped channel will latch the output of the counter at that time If the scan period is much slower than the rate of time frames coming available on the two channels then the data will miss some time frames The scan period can be decreased to capture more time frames The data returned is interpreted as time measured in ticks This data represents the number of ticksize intervals counted during the timing measurement There are four timebase settings 20 ns 200 ns 2 us and 20 us These are often referred to as tick sizes The WBK17 uses a 50 MHz 10 ppm oscillator as a timing source If the input signal has a poor slew rate the timing mode will provide variant results dependant upon the comparator threshold Channel Input a ee a Mapped Channel Input i a a a a S Oe y o J Example of One Channel in Timing Mode Acquisition data o000 WBK17 Counter Encoder Module 987996 WBK17 pg 19 TIMING OPT2 This determines whether the time is to be measured with a 16 bit Counter Low or 32 bit Counter High counter Since time measurements always have the stop at the top option enabled this option dictates whether the measurement has a range of 0 to 65535 ticks or 0
54. sing channel 1 as the Z index therefore relative to Z position information will be acquired on channel 4 Channel 5 is the encoder s B signal input Channel 5 is in period mode the data being acquired will be inversely proportional to the encoder s velocity Two setpoints have been programmed one on channel 4 and the other on channel 5 Channel 4 s setpoint is a window setpoint Detect 4 will go high whenever the encoder s relative position is within the setpoint window Channel 5 s setpoint is a less than value setpoint Detect 5 will go high whenever the encoder s velocity is greater than the setpoint WBK17 Counter Encoder Module 987996 WBK17 pg 33 ee 65545 Ch LowLlirut 527 OF Che HighLirmut Che LowLimut FO Detect3 Detection Example Channel 4 in Encoder Position Mode Channel 5 in Period Mode Detect 4 can be routed to the counter input of another channel that would otherwise be unused If Detect 4 was measured for pulsewidth the data returned in the acquisition would be the amount of time that the encoder position was within the setpoint window If Detect 4 was measured for period the data returned in the acquisition would be the periodicity of the encoder entering the setpoint window If Detect 4 simply clocked a totalizing counter the data returned in the acquisition would be the number of times the encoder entered the setpoint window Any or all of these measurements co
55. th lt q Expansion xq Control In o LS o9 Differential High Speed Amplifier Comparator Counter Input Program Terminal Block oj Asi Aas mable 32 Bit ouplin 1 Blockof 4 fol Ping Programmable Pepounce Counter Analog Filter goug 2 Channels amp 1 COM per Block o9 Programmable aro Threshold 9 me To WaveBook Channel 1 typical of 8 channels o 09 Internal DC to DC Power Supply PREM Digital Re Detection Expansion i Interface o i na r 4 gt i H O 3 i gt t yO 3 d To Digital Inputs i S QA Trigger amp Ext Clock i A a o V Encoder Power i 2s i Terminal Block ISISISISISIGISISIS 3 3 DC Power Input and Expansion o D eg ee Digital Outputs WBK17 Block Diagram The WBK17 can be used with any combination of up to 7 additional WBK signal conditioning modules Together these modules can measure a broad range of signal types and address a broad range of applications A discussion of the following items is presented in Functional Concepts which immediately follows Hardware Setup e AC DC Coupling e Analog Filtering e Comparator e Debounce Circuit e Counter Options e Digital Inputs e Digital Outputs with Pattern Detection WBK17 pg 2 987996 WBK17 Counter Encoder Module Hardware Setup Configuration All WBK17 configurations are controlled by software The WBK17 requires no hardware settings Reference Notes gt Encoder setup
56. ther channel in the scan group Gating Any counter can be gated by the mapped channel When the mapped channel is high the counter will be allowed to count when the mapped channel is low the counter will not count but hold its value Mapped Channel A mapped channel is one of 16 signals that can get multiplexed into a channel s counter module The mapped channel can participate with the channel s input signal by gating the counter clearing the counter etc The 16 possible choices for the mapped channel are the 8 input signals post debounce and the 8 detection signals Start of Scan The start of scan is a signal that is internal to the WBK17 It signals the start of a scan group and therefore pulses once every scan period It can be used to clear the counters and latch the counter value into the acquisition stream Terminal Count This signal is generated by the counter value There are only two possible values for the terminal count 65 535 for a 16 bit counter Counter Low and 4 294 967 295 for a 32 bit counter Counter High The terminal count can be used to stop the counter from rolling over to zero Ticksize The ticksize is a fundamental unit of time and has four possible settings 20ns 200ns 2000ns 20000ns For measurements that require a timebase reference like period or pulsewidth the ticksize is the basic unit of time The count value returned in the scan is the number of ticks that make up the time measurement Count
57. ting but is vibrating due to the machine it is mounted to the debounce feature can be used to eliminate false edges An appropriate debounce time can be chosen and applied to each encoder channel Refer to the Debounce Module section on page 7 for additional information regarding debounce times Relative position and velocity can be obtained from each of the encoders However during an acquisition data that is relative to the Z position can not be obtained until the encoder locates the Z reference During an acquisition data that is relative to the Z position can not be obtained until the encoder locates the Z reference Note that the number of Z reference crossings can be tabulated If the encoder was turning in only one direction then the Z reference crossings will equal the number of complete revolutions This means that the data streaming to the PC will be relative position period I velocity and revolutions You can set detection setpoints on any or all channels Detection setpoints can be used as data markers digital port updates and as mapped channels Each of the WBK17 s eight channels has one detection signal For measurement purposes the detection signals can be routed to an unused counter The number of times a certain detection setpoint has been met can be the output data for this counter channel Reference Note For a complete discussion of setpoints see the section Pattern Detection and Data Markers beg
58. tion data The WBK17 pattern detection module looks at the 16 bit data being returned on a given channel and generates another signal for each channel Detect1 for Channel 1 Detect2 for Channel 2 etc These signals act like data markers for each channel s data whether that data is counts period pulsewidth timing or encoder position A channel s detect signal will be high when the channel s data meets any one of 16 pre programmed setpoint windows the detect signal will be low when the channel s data does not meet any of the setpoint windows The detect signal has the timing resolution of the scan period as seen in the diagram below The detect signal can change no faster than the scan frequency 1 scan period Detectl Detect Detect a E E Acquisition streat ocan Group Ch 1 2 3 4 ete acar Period Example Diagram of Detection Signals for Channels 1 2 and 3 Each channel can have 16 detection setpoints Detection setpoints act on 16 bit data only Since the WBK17 has 32 bit counters for each channel data is returned 16 bits at a time The lower word the higher word or both lower and higher words can be part of the scan group Each channel has 16 detection setpoints for the counter s lower 16 bit value and 16 detection setpoints for the counter s higher 16 bit value Any mix of setpoints can be programmed to drive the detect signal If all lower word setpoi
59. to 4 294 967 295 ticks Encoder Mode WBK17 pg 20 Introduction Rotary shaft encoders are frequently used with CNC equipment metal working machines packaging equipment elevators valve control systems and in a multitude of other applications in which rotary shafts are involved The encoder mode allows the WBK17 to make use of data from optical incremental quadrature encoders When in the encoder mode the WBK17 accepts either differential or single ended inputs and provides power for up to four encoders When reading phase A phase B and index Z signals the WBK17 provides positioning direction and velocity data The WBK17 can receive input from up to four encoders however the WaveView data acquisition program can accept input from only one or two encoders To receive input from three or four encoders with one WBK17 refer to the Programmer s Manual p n 1008 0901 The WBK17 supports quadrature encoders with a 16 bit Counter Low or a 32 bit Counter High counter 5 MHz frequency and x1 x2 and x4 count modes With only phase A and phase B signals 4 channels are supported with phase A phase B and index Z signals 2 channels are supported Quadrature encoders generally have 3 outputs A B and Z The A and B signals are pulse trains driven by an optical sensor inside the encoder As the encoder shaft rotates a laminated optical shield rotates inside the encoder The shield has three concentric circular patterns
60. uld be made in the acquisition along with the channel 4 position data and channel 5 period data It should be noted that the timing resolution of the Detect signals is the scan period Reduce the scan period if more resolution is needed Detect 5 can also be routed to a counter input of another channel that would otherwise go unused If Detect 5 was measured for pulsewidth the data returned in the acquisition would be the amount of time that the encoder velocity was greater than the setpoint If Detect 5 was measured for period the data returned in the acquisition would be the periodicity of the encoder velocity going beyond the setpoint If Detect 5 simply clocked a totalizing counter the data returned in the acquisition would be the number of times the encoder went beyond the setpoint velocity WBK17 pg 34 987996 WBK17 Counter Encoder Module Software Support WaveView contains special software features for WBK17 These features are discussed in the WaveView document module You can use WaveView s spreadsheet style GUI to select a specific counter mode AC DC coupling low pass filter cut off frequency and other WBK17 specific configuration parameters The WBK17 can be configured to make several different types of measurements at the same time but on different channels for example frequency period and quadrature encoder measurements A wide variety of setups is possible In addition to the Out of the Box WaveView software the
61. ut spec is not violated or a fuse may blow The programming setup given below is just a representative of possible options Three Encoders Example Setup Encoder1 A Encoder Mode 1X option 16 bit counter Latch on SOS Encoder1 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 20000ns Encoder2 A Encoder Mode 2X option 16 bit counter Latch on SOS Encoder3 A Encoder Mode 4X option 16 bit counter Latch on SOS Encoder3 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 200ns Encoder1 Z Counter in Totalize mode stop at the top 16 bit counter Encoder2 Z Counter in Totalize mode stop at the top 16 bit counter 4 Encoder2 B Period Mode 1Xperiod option 16 bit counter Map channel doesn t gate Ticksize to 2000ns WBK17 Counter Encoder Module 987996 WBK17 pg 27 WBK17 pg 28 With the encoders connected in this manner there is relative positioning information available on two of the encoders Encoder 1 and 2 but not on the third encoder since there is no Z signal connection for it Therefore only distance traveled can be measured along with velocity for the third encoder Setpoints can be done just like in the previous example The digital output port can be updated by any individual channel a set of selected channels or by all channels Wiring for 4 Encoders The following figure illustrates single ended connections fo
62. z Ticksize nS Averaging Option 15u 500m 20000 Full 32 bit Counter lt 1 ppm Range Hz Ticksize nS Averaging Option 15u 50m 20000 150u 500m 2000 i5m 50 20 l 20 l mso a o 50m Sk 1 5 50k 20 100 1 5 5k 15 500k 1000 15 50k 1000 High Accuracy Frequency Ranges for a 32 bit Value that has little sampling error lt 10ppm lt Ippm imo 20 100 If the input frequency is required to have less than 1 ppm sampling error and is greater than 50kHz use the 15 50kHz lppm range The values returned will have sampling error that is greater than 1ppm but they can be averaged by the PC software to further reduce the sampling error 987996 WBK17 Counter Encoder Module Pulsewidth Mode This mode provides a means to measure a channel s pulsewidth The measurement is the time from the rising edge to the falling edge or visa versa The measurement will be either pulsewidth low or pulsewidth high depending upon the edge polarity set in the debounce module Every time the pulsewidth measurement is latched from the counter the counter 1s immediately cleared and enabled to count the time for the next pulsewidth The pulsewidth measurements are latched as they become available Low Word High Word Increment Channel Input Post Debounce 20 ns 200ns 2000ns 20000 ns To Wavebooks16 Als Channel Inputs Post Debource Alls Detection miznals Pulsew

WBK17 - Measurement Computing

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