Campbell Scientific SDM SDM-SW8A 8-Channel Switch Closure Input Module - Page 11

SDM-SW8A Switch Closure Input Module Parameter & Data Type FunctOp Constant StartChan Constant Mult, Offset Constant, Variable, Array, or Expression Enter The FunctOp is used to determine the result that will be returned by the SW8A. Numeric Function Code 0 Returns the state of the signal at the time the instruction is executed. A 0 is stored for low and a 1 is stored for high. 1 Returns the duty cycle of the signal. The result is the percentage of time the signal is high during the scan interval. 2 Returns a count of the number of positive transitions of the signal. 3 Returns a value indicating the condition of the module: positive integer: ROM and RAM are good negative value: RAM is bad Zero: ROM is bad The first channel that should be read on the SW8A. If the Reps parameter is greater than 1, measurements will be made on sequential channels. A multiplier and offset by which to scale the raw results of the measurement. See the measurement description for the units of the raw result; a multiplier of one and an offset of 0 are necessary to output in the raw units. For example, the TCDiff instruction measures a thermocouple and outputs temperature in degrees C. A multiplier of 1.8 and an offset of 32 will convert the temperature to degrees F. SDMSW8A Example The following program measures all eight channels of an SW8A and outputs a sample of the pulse count to a table once every minute. 'Program Declarations Public SW8ACount(8) 'Data Table Declarations DataTable (CountTab,1,1000) DataInterval (0,1,Min,10) Sample (8,SW8ACount(),FP2) EndTable 'Main Program BeginProg Scan (1,Sec,3,0) SDMSW8A (SW8ACount(),8,0,2,1,1.0,0) CallTable CountTab NextScan EndProg 6.1.2 SDMSpeed Instruction The SDMSpeed instruction is used to change the bit period that the datalogger uses to clock the SDM data. Slowing down the clock rate may be necessary when long cable lengths are used to connect the datalogger and SDM devices. 7