CET Inc.
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2.4 RS-485 Wiring
The PMC-T402 provides a standard RS-485 port that supports the Modbus RTU protocol. Up to 32
devices can be connected on a RS-485 bus. The overall length of the RS-485 cable connecting all
devices should not exceed 1200m.
If the master station does not have a RS-485 communications port, a RS-232/RS-485 or USB/RS-485
converter with optically isolated outputs and surge protection should be used. The following figure
illustrates the RS-485 connections on the PMC-T402.
Figure 2-11 RS-485 Connections
2.5 Digital Output Wiring
The following figure illustrates the Digital Output connections on the PMC-T402:
Figure 2-12 DO Connections
2.6 Residual Current Input Wiring
The following figures illustrate the Residual Current Input connection on the PMC-T402 and typical
wiring with a 3P4W system, respectively:
Figure 2-13 Residual Current Input Connections
Notes:
1) The Residual Current terminals (either IR11 or IR12) should be left open and should not be connected to ground if unused.
Otherwise, doing so would damage the device.
