Campbell Scientific CR10 CR10 Measurement and Control - Page 113

SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPEES Input Location Labels: 1:Rain (mm) 2:1Smin tot *1 01: 60 Table 1 Programs Sec. Execution Interval 01: 01: 02: 03: 04: 05: 06: P3 1 1 2 1 .254 0 02: P92 01: 0 02: 15 03: 10 0031: : P80 3 02: 2 04: P72 0012:: 1 1 05: P89 01: 2 02: 2 0034:: 0 30 06: P80 01: 02: 1 25 07: P77 01: 110 08: P7O 01: 1 02: 2 Pulse Rep Pulse lnput Chan Switch Closure Loc [:Rain (mm)] Mult Offset lf time is minutes into a minute interval Set high Flag 0 (output) Set Active Storage Area Input Storage Area Array lD or location Totalize Rep Loc Rain (mm) lf XF X Loc 1Smin tot F Then Do Set Active Storage Area Final Storage Area 1 Anay lD or location RealTime Day,Hour-Minute Sample Reps Loc 15min tot 09: P95 End 10: P End Table 1 8.3 USING CONTROL PORTS AND LOOP TO RUN AM416 MULTIPLEXER This example uses an AM416 to measure 16 copper-constantan thermocouples and 1 6 Model223 soil moisture blocks. The sensors are read every ten minutes and the average value output once an hour. The multiplexer is housed in an AM-ENCT enclosure to minimize thermocouple errors created by thermal gradients. A107 Temperature Probe is centrally located on the multiplexer board and used as a thermocouple temperature reference. The AM416 switches lhe 223 moisture block out of the circuit when it is not being measured. This eliminates the need for the blocking capacitors used in the model 227 soil moisture block. The 223 blocks are about one fifth the cost of the 227 blocks. Control ports are used to reset the AM416 and clock it through its channels. The sequence of the program is: . Measure the 107 probe located at the o AM416 for TC temperature reference. CR10 sets the port high which resets the . o . AM416. A loop is entered; within each pass: The port clocking the AM416 is pulsed. The connected TCs and moisture blocks are measurec. o CRlO sets the pod controlling AM416 reset low. o Soil moisture measurements are converted to block resistances. The input location in which the temperature and soil moisture measurements are stored is indexed to the loop counter (lnstruction 87, Section 12). An indexed location is incremented by one with each pass through the loop. For example, on the first pass temperature is stored in Location 2, and soil moisture in Location 18. On the second pass temperature is stored in Location 3, and soil moisture in Location 19. After 16 loop passes; temperature and soil moisture measurements occupy Locations 2 through 17 and 18 through 33, respectively. Connections are shown in Figure 8.3-1. 8-3