SDM-INT8 8 Channel Interval Timer Revision: 12/11 C o p y r i g h t © 1 9 8 9 - 2 0 1 1 C a m p b e l l S c i e n t i f i c , I n c .
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SDM-INT8 Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Overview.......................................................................2 2. Specifications ..............................................................3 3. Connections .................................................................4 4. Power Supply Considerations ....................................5 5.
SDM-INT8 Table of Contents Appendices A. Address Jumper ...................................................... A-1 B. Processing Time Limitations ................................. B-1 C. INT8 Input Schematic..............................................C-1 List of Figures 1. SDM-INT8 Front Panel ............................................................................. 1 2. Voltage Input Options, Edges and Thresholds........................................... 2 3. Wiring Diagram ........................
SDM-INT8 8 Channel Interval Timer FIGURE 1.
SDM-INT8 8 Channel Interval Timer 1. Overview The 8 channel Interval Timer (INT8; see Figure 1) is a measurement module which outputs processed timing information to a 21X, CR10(X), CR23X, CR800, CR850, CR1000, CR3000, CR5000, or CR9000(X) datalogger. Each input channel is programmed to detect transitions from low or high level voltage inputs (Figure 2). Period, pulse width, frequency, counts, and time intervals are output to the datalogger for further processing/logging. FIGURE 2.
SDM-INT8 8 Channel Interval Timer 2. Specifications Operating voltage: 9.6 V to 16 V DC Current drain: 13 to 20 mA active, 400 microamp quiescent Environmental: -25 to +50 degrees Celsius 0 to 90% RH (non-condensing) Number of channels: 8 Maximum timing measurement: 16.7 seconds Resolution: ± 1 microsecond Dimensions: 8 x 5 x 1 in (13 x 20 x 2 cm) Weight: 1.
SDM-INT8 8 Channel Interval Timer Minimum AC voltage RMS 20 mV 50 mV 150 mV 2.5 V - 20 V Max Freq. (Hz) 100 400 1000 4000 3. Connections The CABLE5CBL-L cable connects the SDM-INT8 to a datalogger. The datalogger-to-SDM-INT8 connections are shown in Figure 3. Please note that the SDM-INT8 connects to the CR9032 CPU module of the CR9000X and the CR9080 PAM module of the CR9000. INT8s are shipped from the factory with a 10K Ohm resistor attached to the terminal strip for the convenience of 21X user.
SDM-INT8 8 Channel Interval Timer CR800, CR850, CR9032 (CR9000X), CR9080 (CR9000), CR10(X), CR23X, or CR1000 CR3000, CR5000 12V G SDM-C3 SDM-C2 SDM-C1 10K OHM RESISTOR FIGURE 3. Wiring Diagram 4. Power Supply Considerations The datalogger's power supply is typically used to power the INT8, however, an auxiliary supply may be used as shown in Figure 3. When selecting a power supply, consideration must be given to the active current drain and the active time of the INT8.
SDM-INT8 8 Channel Interval Timer 5.1 CRBasic Programming 5.1.1 Instruction SDMINT8 The SDMINT8 instruction is used to program and control the SDMINT8 interval timer module. Description of the instruction follows. Syntax SDMINT8 (Dest, SDMAddress, Config8_5, Config4_1, Funct8_5, Funct4_1, OutputOpt, CaptureTrig, Mult, Offset) Dest: Dest is used to specify the array where the results of the instruction are stored.
SDM-INT8 8 Channel Interval Timer Function8_5: The Function8_5 parameter is a four digit code used to program the timing function of channels 5 through 8. Similar to the Config parameters, digits represent the channels in descending order from left to right (e.g., 8 7 6 5). See Section 6.3 for further details about these functions.
SDM-INT8 8 Channel Interval Timer as a trigger to start making measurements. The Dest parameter must be dimensioned large enough to receive the captured events. -9999: Initiates a self memory test of the INT8. A numeric code is returned to indicate the results of the test.
SDM-INT8 8 Channel Interval Timer The equation used to calculate the bit rate depends on the datalogger used. The datalogger will round down to the next faster bit rate. Equation for CR800, CR850, and CR1000: bit_rate=INT((k*72)/625)*Resolution Where: k= the value entered in BitPeriod Resolution=8.68 microseconds Equation for CR3000: bit_rate=INT((k*144)/625)*Resolution Where: k= the value entered in BitPeriod Resolution= 4.34 μsec.
SDM-INT8 8 Channel Interval Timer TABLE 2. Instruction 101 Parameter 01: 02: 03: 04: 05: 06: 07: 08: 09: Data Type 2 4 4 4 4 4 4 FP FP Description Address (Section 6.1) *Input config; channels 8,7,6,5 *Input config; channels 4,3,2,1 **Function; channels 8,7,6,5 **Function; channels 4,3,2,1 ***Output option Loc Mult Offset Execution time: 2.3 ms + 1.
SDM-INT8 8 Channel Interval Timer connected to the datalogger must have a unique address. See Appendix A for details on changing the address. 6.2 Input Configuration Each of the 8 input channels can be configured for either high level or low level voltage input, and for rising or a falling edge detect (see Figure 2). One digit (0,1,2, or 3) is specified to configure each channel, as shown below.
SDM-INT8 8 Channel Interval Timer 6 - Low resolution frequency (kHz)-For this function to return low resolution data, it must be the only function used in the instruction. If this is not the only function used in the instruction, it returns high resolution data, the same as Function 2. Higher frequencies may be measured if fewer channels are used (see Section 2, Specifications). For this function, any data value less than 1 is returned as 0.
SDM-INT8 8 Channel Interval Timer Channel 1: Channel 3: Channel 4: Channel 5: Channel 2,6,7,8: frequency (2) counts on channel 2 since channel 1 (5) frequency (2) time since previous Channel (3) none (0) Channel 1: RPM may be calculated from crankshaft frequency. Channel 3: Flywheel teeth count between the crankshaft reference pulse, and the spark gives reference to the crank angle.
SDM-INT8 8 Channel Interval Timer TABLE 3. Input Frequency (kHz) at Which Processing Time Equals Measuring/Storing Time N 1 2 3 4 5 6 7 8 1,2,6,7 3 4 5 8 * 3.5 2.1 1.4 .99 .75 .59 .47 3.4 1.6 0.99 0.70 0.53 0.42 0.34 0.28 3.7 1.7 1.1 0.76 0.57 0.45 0.37 0.30 0.14 - 0.05F2 0.07 - 0.02F2 0.05 - 0.02F2 0.04 - 0.01F2 0.03 - 0.01F2 0.02 - 0.01F2 3.4 - 0.81F2 1.6 - 0.38F2 0.99 - 0.24F2 0.70 - 0.17F2 0.53 - 0.13F2 0.42 - 0.
SDM-INT8 8 Channel Interval Timer TABLE 4. Sampling Interval (Seconds) to Accumulate 8000 Unprocessed Events for Functions 1,2,6,7 Input Freq. kHz 1.1 1.3 1.5 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 3 8.91 6.73 5.33 4.36 3.65 4 Number of Channels 5 6 7 6.55 4.64 3.50 2.76 2.24 1.86 1.57 1.35 1.17 1.03 .91 .81 .73 5.62 3.68 2.64 2.00 1.57 1.27 1.05 .88 .75 .65 .57 .50 .45 .40 .36 .33 .30 7.97 4.21 2.67 1.87. 1.38 1.07 .86 .7 .58 .49 .42 .37 .32 .28 .25 .23 .20 .19 .
SDM-INT8 8 Channel Interval Timer FIGURE 4. Example of Multiple Beginnings and Endings 6.4.2 Option 0: Execution Interval Averaging When Option 0 is selected, the result from each channel is a value averaged over the interval since the INT8 was previously addressed. Normally this would be the execution interval. The value returned to the datalogger is the average at hand when the INT8 is addressed.
SDM-INT8 8 Channel Interval Timer Assume the input frequency is 0.5 Hz, and the execution interval of Instruction 101 is 10 Hz. The datalogger input location is updated at about 0.5 Hz if a change occurred, not every time the INT8 is addressed. An example of an intermittent signal is a Cub Scout Pinewood Derby where the measured event is the elapsed time of a race, but several minutes separate each heat. Three cars per heat are gravity powered down a straight track.
SDM-INT8 8 Channel Interval Timer Since the number of values returned may be variable, making it difficult to assign a fixed number of input locations, the Capture All Events Option outputs data directly to the datalogger's Final Storage when Instruction 101 is executed. If the Output Flag is not set when the instruction is executed, the datalogger commands the INT8 to start measuring, and no results are returned.
SDM-INT8 8 Channel Interval Timer TABLE 5. Definition of Test Memory Option Output Output Definition positive integer negative integer 0 -0 = = = = ROM signature, good RAM ROM signature, bad RAM bad ROM bad ROM, bad RAM A result of executing Option 9999-- is that the program residing in the INT8 is deleted, and the INT8 goes into the low current drain standby mode. To initiate INT8 measurements, SDMINT8 or Instruction 101 must be executed without 9999--. 6.
SDM-INT8 8 Channel Interval Timer When using the Capture All Events Option (no averaging), the data are directed to Final Storage of the datalogger rather than Input locations. The first execution of Instruction 101 will program the INT8. Subsequent executions of Instruction 101 with the Output Flag set will output all events to Final Storage. If the Output Flag is not set, the INT8 will be reinitialized with out returning any data.
SDM-INT8 8 Channel Interval Timer ‘Declare Public Variables Public Int8(5) Public PulseCh(2) Dim I ‘Define Data Tables DataTable (Dat5min,1,-1) DataInterval (0,5,Min,10) average (5,Int8(),FP2,False) EndTable ‘Main Program BeginProg Scan (5,Sec,0,0) ‘measure 03101 on P1 & P2 WS_ms: PulseCount (PulseCh(1),1,1,1,1.75,.2) PulseCount (PulseCh(2),1,2,1,1.75,.2) ‘measure 03101 on SDMINT8 channel 1 through channel 5 SDMINT8 (Int8(),3,0002,2222,0002,2222,0,1,1.75,.2) ‘For I = 1 to 5 ‘If Int8(I)<0.
SDM-INT8 8 Channel Interval Timer Parameter 6 (Capture All Events) is programmed for 20--to capture edge times on channels 1-5 until 20 edges are received on channel 1. Flag 2 is used in the example to indicate the start of the cranking. In actual test program, this flag could be set in response to an ignition switch measurement indicating the start of the test. When the ignition is turned on (Flag 2 set), Instruction 101 is called, and the INT8 is programmed.
SDM-INT8 8 Channel Interval Timer 3: Beginning of Loop (P87) 1: 1 Delay 2: 20 Loop Count loop to make a 10 sec.
SDM-INT8 8 Channel Interval Timer *Table 1 Programs 01: 1 Sec. Execution interval 1: SDM-INT8 (P101) measure wind speed 1: 00 Address Option 2: 0022 Chan8765=HLrise/HLrise/LLrise/LLrise/ 3: 2222 Chan4321=LLrise/LLrise/LLrise/LLrise 4: 0022 Chan8765=none/none/kHz/kHz/ 5: 2222 Chan4321=kHz/kHz/kHz/kHz/ 6: 0 Execution interval averaging (1 second) 7: 1 Loc [:m/s ] 8: 98.
SDM-INT8 8 Channel Interval Timer *Table 1 Programs 01: .125 Sec.
SDM-INT8 8 Channel Interval Timer 11: Set Active Storage Area (P80) 1: 1 Final Storage Area 1 2: 1 Array ID or location 12: Sample (P70) 1: 200 Reps 2: 1 Loc 13: Do (P86) 1: 10 Set high Flag 0 (output) 14: Set Active Storage Area (P80) 1: 1 Final Storage Area 1 2: 2 Array ID or location 15: Sample (P70) 1: 200 Reps 2: 201 Loc 16: Do (P86) 1: 10 Set high Flag 0 (output) 17: Set Active Storage Area (P80) 1: 1 Final Storage Area 1 2: 3 Array ID location 18: Sample (P70) 1: 200 Reps 2: 401 Loc 19: Do P86 1
Appendix A. Address Jumper The address is factory set at address 00. Figure A1 (also shown inside the INT8 cover) shows the 16 possible positions and their corresponding address. Use the addresses shown in Figure A1 in Instruction 101. The address block requires soldering to change the address. If two or more INT8s are to be used on the same datalogger, one can remain at address 00, while the others must be changed. Disconnect power before opening the case and soldering.
Appendix B. Processing Time Limitations With the exception of the Capture All Events Option or when all channels are programmed for low resolution frequency (Function 6), the INT8 is performing two tasks simultaneously: (1) measuring and storing, and (2) doing the processing necessary for the final calculations of averages.
Appendix B. Processing Time Limitations If the Tt for Output Option XXXX is greater than the specified interval, the extra time will be added to the execution time of Instruction 101. Example 1 Given: Output Option = XXXX Specified interval = S = 500 ms Function = frequency (Function 2) Number of channels measured = N = 6 Average input frequency = F = 1kHz Find: Total Processing Time, Tt Solution: Tt = To+ΣTi = To+T2 = 0.511*S+Et*(.034+.010*N) +0.
Appendix B. Processing Time Limitations Example 3 N = number of channels measured Given: F = Frequency of input signal, kHz Function = frequency (Function 2) Output Option = XXXX with specified sampling interval, S Find: Sampling interval, S, such that the number of unprocessed events is ≤ 8000 Solution: The interval required to process 8000 events after the sampling interval is Tt-S, therefore; (Tt-S)*F*N≤8000 S≥Tt-(8000/(F*N)) S≥(0.511*S+Et*(.034+.010*N)+0.
Appendix B.
Appendix C.
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