- Check the power supply wiring.
- Check whether the power supply voltage meets the specifications.
- Check the polarity of the input wiring.
- Measure the voltage between the input terminal (-) and COM. The normal range is 1–5 VDC.
- Measure the voltage between the input terminal (+) and COM. The normal range is 20 VDC or higher.
- If including the transmitter power supply, use a tester with a sync function.
- If the output signals is of the current specifications, attach an external 250 Ω resistance and measure the voltage.