Checking Linear Resistance Inputs; Checking Linear Voltage 0-10 Vdc Inputs - Trane Tracer MP581 Hardware Installation

Chapter 5 Wiring inputs and outputs
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Checking linear resistance inputs

To check linear resistance inputs for proper operation:
1. Make sure that the sensor is connected.
2. Set the multi-meter to measure Vac, then measure the voltage across
the input at the signal and common screw terminals.
The measured voltage should be less than 0.1 Vac. If the voltage is
greater than this, resistance readings may change erratically.
3. Set the multi-meter to measure Vdc, then measure the voltage across
the input at the signal and common screw terminals.
The measured voltage should be less than 0.1 Vdc. If the voltage is
greater than this, resistance readings may be offset.
CAUTION
Equipment damage!
Continue to step 4 only if you completed steps 2 and 3 successfully.
Measuring resistance may damage the meter if the voltage is too high.
4. Set the multi-meter to measure resistance. If you completed steps 2
and 3 successfully, measure the resistance across the input at the sig-
nal and common screw terminals.
The resistance should be between 100 Ω and 20 kΩ.
Checking linear voltage 0–10 Vdc inputs
The following test works only for 0–10 Vdc inputs that have their own
power supply.
To check linear voltage 0–10 Vdc inputs for proper operation:
1. Make sure that the sensor is connected and powered on.
2. Set the multi-meter to measure Vac, then measure the voltage across
the input at the signal and common screw terminals.
The measured voltage should be less than 0.1 Vac. If the voltage is
greater than this, sensor readings may change erratically.
3. Set the multi-meter to measure Vdc, then measure the voltage across
the input at the signal and common screw terminals.
The measured voltage should be between 0 and 10 Vdc. If the voltage
is greater than 10 Vdc, check the connections at the controller. If it is
less than 0 Vdc, check the meter and input connections.
4. Force a change in the sensor reading.
5. Use the multi-meter to confirm that the change appears at the correct
input on the terminal board.
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