Remote Technologies RPC-320 - Manual (Page 40)

ANALOG INPUT SECTION 10
Page 10-5 RPC -320
The outpu t voltage fro m the tem peratur e sensor is
doubled by jumpering H1[5-7]. While this does not
change the range the unit operates at, it does change
increase temperature m easurement sensitivity.
Data logging on a timer tick
Some applications require that data is read at fixed
intervals. The O NTI CK con struct is used to take data in
intervals from 0. 01 to 327 seconds. The exam ple below
takes 1 sample per second until 100 samples have been
obtained.
10 DIM A(100)
20 ONTICK 1,500
30 REM THE REST OF YOUR PROGRAM
40 REM CONTINUES
80 GOTO 30
500 A(N) = AIN(3)
510 N=N+1
520 IF N = 100 THEN ONTICK 0,500
530 RETI
MEASURING HIGHER VOLTAGES
Voltages higher than + 5V are measur ed by inserting a
series r esistor to the inp ut.
The table below shows resistor values for some input
voltages using the 0-5V range.
Maximum
Input Voltage
Resistor
6 20K
12.5 150K
24 380K
Use the following formula to determine the series
resistance necessar y for a m aximum voltage input:
Rs = Vi * 20000 - 100000 0 - 5V range
Rs = Vi * 40000 - 100000 0 - 2.5V r ange
Rs is the re sistor value in ohms in ser ies with the inpu t.
Vi is the maximum input voltage. W hen Rs is negative
or zero, a series resistor is not necessary.
A high Rs v alue can ca use noisy r eadings. This is
because the resistor acts as an antenna. To reduce noise,
place a 0.1 mfd to 1 mfd capacitor betw een the input
terminal and ground.
NOTE: When an input voltage exceeds the input range,
other channel values are affected.