Download ControlLogix Controllers

Communicate over Networks
Chapter 3
Additional Resources
For additional information, consult these publications:
· Logix5000 Controllers General Instructions Reference Manual,
publication 1756-RM003
· Logix5000 Controllers Common Procedures Programming Manual,
publication 1756-PM001
Modbus Support
To use Logix5000 controllers on the Modbus protocol, establish a serial port
connection and execute a specific ladder-logic routine. The controller project is
available with RSLogix 5000 programming software.
Additional Resources
For additional information, consult Using Logix5000 Controllers as Masters or
Slaves on Modbus Application Solution, publication CIG-AP129.
DH-485 Network
Communication
For DH-485 communication, use the serial port of the controller. The
controller can send and receive messages to and from other controllers on a
DH-485 network. The DH-485 connection supports remote programming
and monitoring via RSLogix 5000 programming software. However, excessive
traffic over a DH-485 connection can adversely affect overall performance and
lead to timeouts and decreased RSLogix 5000 configuration performance.
IMPORTANT
Use Logix5000 controllers on DH-485 networks only when you
want to add controllers to an existing DH-485 network. For new
applications with Logix5000 controllers, we recommend you
use networks in the NetLinx open architecture.
The DH-485 protocol uses RS-485 half-duplex as its physical interface. RS-485
is a definition of electrical characteristics, not a protocol. You can configure
the RS-232 port of the ControlLogix controller to act as a DH-485 interface.
By using a 1761-NET-AIC converter and the appropriate RS-232 cable
(1756-CP3 or 1747-CP3), a ControlLogix controller can send and receive data
on a DH-485 network.
Publication 1756-UM001H-EN-P - July 2008
41