User's Manual

System Start-up Procedures

Part No. 430-4G-200-00-000

5-3

Before a device can be connected to an RS-485 subsystem, it must be checked for ground

faults. An uncorrected ground fault can damage all devices connected to the RS-485

communication line.

To check for a ground fault on the RS-232 to RS-485 converter:

1. Apply power to the RS-232 to RS-485 converter.

2. Connect the signal ground of the RS-485 line through a 10k ohm current-limiting resistor to

the signal ground of the RS-232 to RS-485 converter. There should be no more than 1 volt

across the resistor.

5.3. RS-232

TO RS-485 CONVERTER GROUND FAULT CHECK

To check for a ground fault on a new V-Station 4G or V-Flex 4G device:

1. Apply power to all devices already successfully connected to the RS-485 line.

2. Power up the new device but do not connect it to the RS-485 line.

3. Connect the signal ground of the RS-485 line through a 10k ohm current-limiting resistor to

the signal ground of the V-Station 4G device.

4. There should be no more than 1 volt across the resistor. If there is, find and clear the fault.

5. Repeat Steps 1 through 3 with each of the RS-485 signal lines (+ and -).

6. Connect the new device to the RS-485 line only if no ground fault is found.

5.4. D

EVICE GROUND FAULT CHECK