6.6.2 Configure Modbus/RS-485 communications
ProLink III Device Tools > Configuration > Communications > RS-485 Terminals
Field Communicator Configure > Manual Setup > Inputs/Outputs > Communications > Set Up RS-485 Port
Overview
Modbus/RS-485 communications parameters control Modbus communication with the
transmitter's RS-485 terminals.
Procedure
1. Set Disable Modbus ASCII as desired.
Support for Modbus ASCII limits the set of addresses that are available for the
transmitter's Modbus address.
Modbus ASCII support
Available Modbus addresses
Disabled 1–127, excluding 111 (111 is reserved to the service port)
Enabled 1–15, 32–47, 64–79, and 96–110
2. Set Protocol to match the protocol used by your Modbus/RS-485 host.
Option
Description
Modbus RTU (default) 8–bit communications
Modbus ASCII 7–bit communications
If support for Modbus ASCII is disabled, you must use Modbus RTU.
3. Set Modbus Address to a unique value on the network.
4. Set Parity, Stop Bits, and Baud Rate as appropriate for your network.
5. Set Floating-Point Byte Order to match the byte order used by your Modbus host.
Code
Byte order
0 1–2 3–4
1 3–4 1–2
2 2–1 4–3
3 4–3 2–1
See the following table for the bit structure of bytes 1 through 7.
Integrate the meter with the control system
Configuration and Use Manual 85
To Next Page
Loading...
