Campbell Scientific S3497X TC Psychrometer PROM and Cooling Current Interface - Page 8
Output Format, 7. Example, Peltier Thermocouple Psychrometer, Acknowledgment
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25 PELTIER THERMOCOUPLE PSYCHROMETER 6. OUTPUT FORMAT Instruction 25 stores all readings from a given TCP sequentially in Input Storage. The base temperature is first, followed by the zero reading, and then the sequence of wet-bulb readings with the zero reading subtracted. The series of readings from the next TCP then follows, etc. The number of Input Storage locations allocated must be based upon the number of TCPs excited by one A3497 Interface and the number of wet-bulb readings per TCP. When the Loop Instruction is used, the readings from each A3497's TCPs use the same Input Storage. The readings associated with a given A3497 must be transferred to Final Storage before progressing to the next A3497. All the readings associated with one A3497 can be transferred to Final Storage using a single Sample Instruction (#70) and the appropriate number of "repetitions." However, this technique results in the reading from all the TCPs being blocked together in one Output Array. By setting the Output Flag and using a Sample Instruction for each TCP associated with the A3497, the readings for each TCP are blocked into their own Output Array and contain their own unique Output Array ID. An example of this latter type of output is shown in Table 2. 7. EXAMPLE The following program example was used to generate the data shown in Table 2. Four Model PST-55 Wescor and four Model 74 Merrill TCPs were read using two A3497 Interfaces. The program makes use of the Loop Instruction. The following criteria were used: 1. Number of wet-bulb readings per TCP - 29 2. Heating/cooling current - 4.5 mA (-1900 mV) 3. Heating duration - 5 s 4. Delay after heating - 15 s 5. Cooling duration - 15 s 6. Delay after cooling - 0 s 7. Delay between wet-bulb measurements - 0 s 8. Input Storage (31 locations per TCP): First TCP Loc 2 - Loc 32 Second TCP Loc 33 - Loc 63 Third TCP Loc 64 - Loc 94 Fourth TCP Loc 95 - Loc 125 9. Input Card - 1 10. First measurement channel - 1 11. Excitation Card - 1 12. First excitation channel - 1 4 Acknowledgment: CSI gratefully acknowledges the assistance of Dr. Raymond W. Brown, U.S. Forest Service, Intermountain Forest and Range Experiment Station, Logan, Utah and the use of his facilities in testing the TCP software. 01: P 01: 1 02: 1 17 Panel Temperature IN Card Loc [:Panel T ] 02: P 01: 0 02: 2 87 Beginning of Loop Delay Loop Count 03: P 01: 4 02: 2 03: 1 04: 2 05: 1 06: 1 07: 1 08: 1 09: -1900 10: 1500 11: 1500 12: 1500 13: 0 14: 0 15: 29 25 Thermocouple Psychrometer Psychrometers per A3497 Loc:[:TCP 1 #1 ] Ref Temp Loc Panel T 2=Measure HI WRT GND, 1=LO IN Card IN Chan EX Card EX Chan mv Excitation Heating (time units=.01sec) Delay before 0 measurement Cooling duration Delay before wet bulb meas. Delay between wet bulb meas. Wet bulb measm'ts per psychr. 04: P 01: 10 86 Do Set high Flag 0 (output) 05: P 01: 31 02: 2 70 Sample Reps Loc TCP 1 #1 06: P 01: 10 86 Do Set high Flag 0 (output) 07: P 01: 31 02: 33 70 Sample Reps Loc TCP 2 #1 08: P 01: 10 86 Do Set high Flag 0 (output) 09: P 01: 31 02: 64 70 Sample Reps Loc TCP 3 #1 10: P 01: 10 86 Do Set high Flag 0 (output)