ABB NGC8206 User Manual page 218

3) If any inaccuracy exists, investigate the wiring errors or damaged wires.
2101510 Rev. AG
When the unit is transmitting data, the voltage should vary between +5 VDC
and 0 VDC. This would indicate that the RRTS is working correctly.
If a communication problem still exists and the unit has
passed the tests in steps 1 and 2, additional testing will be
required.
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