Configuration and Use Manual
MMI-20025166
B.2.3 Make a Modbus/RS-485 connection from ProLink III to the
transmitter
This connection type uses Modbus protocol and commands to communicate with the transmitter over an
RS-485 network. You can make a Modbus/RS-485 connection to the transmitter's RS-485 terminals
(Channel E) or to any point on the network.
Prerequisites
•
Channel E activated on the transmitter
•
Installation kit
•
An available serial port or USB port
•
Adapters as required (for example, 9-pin to 25-pin)
Procedure
1. Attach the signal converter to the serial port or USB port on your PC.
2. To connect directly to the transmitter terminals:
a) Open the transmitter wiring compartment.
CAUTION
If the transmitter is in a hazardous area, do not open the wiring compartment while the
transmitter is powered up. Opening the wiring compartment while the transmitter is
powered up could cause an explosion. To connect to the transmitter in a hazardous
environment, use a connection method that does not require opening the wiring
compartment.
b) Connect the leads from the signal converter to terminals 9 (RS-485/A) and 10 (RS-485/B).
Tip
Usually, but not always, the black lead is RS-485/A and the red lead is RS-485/B.
Configuration and Use Manual
Using ProLink III with the transmitter
March 2019
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