GE Industrial Solutions POWER LEADER ModBus Monitor - Manual (Page 17)

POWER LEADER Modbus Monitor
Chapter 2 – Installation
11
When the assembly is complete, plug the connector into
port labeled Segment A on the side of the Monitor, as
shown in Figure 10.
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Figure 10. RS-485 port and RS-485 connector pinouts.
The connectors labeled IN should be wired to the cable
coming from the host (or previous device), or should be
terminated if the Monitor is the first device on the
Modbus segment. The
OUT connectors are wired to the
RS-485 IN connector of the next Modbus device, or
terminated if the Monitor is the final device on the
Modbus segment. Please study and follow the RS-485
grounding considerations and termination rules below to
ensure the correct operation of your Modbus segments.
If the Monitor is to be connected to a second Modbus
segment, follow the procedures outline above to wire the
connector, and plug it into the port labeled Modbus
Segment B on the side of the Monitor. Note that
termination considerations are independent for each
segment; i.e., the Monitor may need to be terminated for
one or both RS-485 segments, or for neither, if it is
positioned in the middle of the segment(s).
RS-485 Termination Considerations
Per the EIA485 standard, every RS-485 network must be
terminated at both ends. If the Modbus Monitor is the
first device, place the supplied 120-ohm, 1/2-watt
resistor between the + and - connectors of the
RS-485 IN
port. If the Modbus Monitor is the last device, place the
supplied 120-ohm, 1/2-watt resistor between the + and -
connectors of the
RS-485 OUT port.
Figure 11 illustrates appropriate termination of an RS-
485 segment at the Modbus Monitor
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Figure 11. RS-485 Terminations.