Appendix A Monitoring Resistance And Switch Status; Measuring Resistance; Monitoring Switch Status - ACR Electronics SmartReader Plus Reference Manual

SmartReader Plus Data Loggers
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1.15

APPENDIX A Monitoring Resistance and Switch Status

1.15.1

Measuring Resistance

You can also use your SmartReader Plus 1, 2, 4 and 8 model loggers to monitor resistance,
instead of just temperatures. This capability allows you to monitor devices other than just
thermistors (for example, potentiometers, level indicators or any other device that varies
resistance in accordance with a known parameter).
To use the thermistor temperature channel on your SmartReader Plus logger to measure
resistance, you must change the channel's equation number to the one for resistance. To do
this, select Equation 44 - Resistance when setting up the logger in TrendReader software.
The highest resolution of the resistance measurements occurs at a 10k ohms midpoint.
1.15.2

Monitoring Switch Status

You can also use your SmartReader Plus 1, 2, 4 and 8 model loggers to record the status of
uncommitted mechanical switch contacts (see Figure A-1). The switch you want to monitor
must be a "dry" contact, which means that it must have no connection to any type of voltage,
power or ground.
To use the thermistor temperature channel on your SmartReader Plus data logger to monitor
switch status, you must change the channel's equation number to the one for switch status.
To do this, choose Equation 41 - Switch Status when setting up the logger using
Monitoring Resistance
and Switch Status
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