Getting Started
248083336-1 Rev 3 3-7
WARNING:
Using a
properly configured
RS232 to RS485
conversion kit is
imperative BEFORE
attempting to use RS-485
COM mode with a PC.
Failure to heed this
warning can result in
damage to PC,
instrument or both.
For a detailed description of the MODBUS registers and commands,
please see “Supported MODBUS Commands” on page A-1.
Attaching the 3104P or 5104P to an RS-485 network requires special
attention to topology (wiring scheme of network) before and after the
design phase to make sure the 3104P or 5104P and other instruments
will perform as expected.
In an RS-485 network, the 3104P or 5104P must be used in a "star" or
hub-based configuration. Do NOT attempt to configure it for daisy
chaining. Verify with vendor that +24 VDC is not present on pin 7 of
the RJ45 connectors or damage may result.
WARNING:
Be
advised that +24 VDC is
present on pin 7 of the
RS485 port. Make sure
that the RS485 hub or
switch used does NOT
have +24 VDC present on
pin 7 or damage to the
instrument, hub or both
may result.
A standard Cat5 cable is used to connect the 3104P or 5104P to an RS-
485 network. Table 3-2 illustrates the RS-485 RJ45 pins and the
signals assigned.
Figure 3-5 Rear Connector Pin Assignments
Table 3-2 RS-485 RJ-45 Pinouts
RJ-45 Pin Signal Name
1 RESERVED for future use
2 RESERVED for future use
3 RESERVED for future use
4 RS-485B
5 RS-485A
6 RESERVED for future use
7 +24 volts
8 GND
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