Campbell Scientific AM16/32B AM16/32B Relay Multiplexer - Page 18

AM16/32B Relay Multiplexer NOTE If the time between the falling edge of the 5 ms RESET pulse and the next rising edge of RESET or CLK is longer than 125 ms, the AM16/32B will go into Mode A. Section 4.1.2.3, Datalogger Connection/Instruction, includes a portion of a CR1000 program that shows the instructions used to go into Mode B and jump to channel 6. 5 ms (±1 ms) AA5dTdmTdodrosreEe(Es+nssnst-e2teMMrmrBoosBdd) ee Reset Clk > 1ms > 1ms ((00 --17050mms)) NNootete::ifif>>112050mss tthhee BB AAddddrreessss mmooddee is Aborrtteedd.. AAllssoo,,AAbboorrttccaannhhaappppeennifif>>112050mmss ttimimeebbeetwtweeeennCClkl'ks'.s En ters B addressing m o de Address=Chan 3 Chan 3 Selected (Relays m ake co ntact) Ad vance to Chan 4 (Relays m akes contact) Note: if th e B m od e is aborted, th en this event w ou ld select Mux Chan 1 FIGURE 4-2. Diagram showing advancement of channels using clocking Mode B 4.1.2.3 Datalogger Connection/Instruction With the 21X and CR7 dataloggers, switched excitation is generally used to clock the multiplexer (instruction Excitation with Delay (P22) configured for 5000 mV excitation). If no switched excitation channel is available, it is possible to clock using control ports. See Section 5.1, CRBasic Programming, for details. In the case of the CR5000, CR3000, CR800, CR850, CR1000, CR23X, and CR10(X), a control port is generally used to clock the multiplexer. Instruction Do (P86) with the pulse port option (command code 71 through 78) generates a 10 ms pulse which works well. The CR5000, CR3000, CR800, CR850, and CR1000 uses a control port controlled by PortSet(), Delay(), and SubScan()/NextSubScan to create the Clock pulses (see program example in Section 5.3, General Programming Considerations). If several multiplexers are required, a CR5000, CR3000, CR800, CR850, CR1000, CR10(X), or CR23X control port can source sufficient current to drive up to six AM16/32B CLK or RES inputs wired in parallel. 8