Allen-Bradley controllogix 1756-L55M12, User Manual

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Publication 1756-UM001G-EN-P - January 2007
Communicate over Networks 31
Serial Network
Communication
The ControlLogix controller has one built-in RS-232 port.
DF1 Modes for Logix5000 Controllers
Functions Required
•
Communicates between a controller and other
DF1-compatible devices using DF1 protocols.
•
Uses modems.
•
Controls SCADA applications.
•
Controls ASCII devices.
Built-in serial port
•
Requires additional RS-232 connections.
•
Requires RS-422 and/or RS-485 connections.
1756-MVI
1756-MVID
IMPORTANT
Limit the length of RS-232 serial cables to 15.2 m (50 ft).
Mode Functions
DF1
point-to-point Communication between the controller and one other DF1-protocol-compatible device.
This is the default system mode. Default parameters are:
•
Baud Rate: 19200
•
Data Bits: 8
•
Parity: None
•
Stop Bits: 1
•
Control Line: No Handshake
•
RTS send Delay: 0
•
RTS Off Delay: 0
This mode is typically used to program the controller through its serial port.
DF1 master
mode
•
Control of polling and message transmission between the master and slave nodes.
•
The master/slave network includes one controller configured as the master node and up to 254 slave nodes. Link slave
nodes using modems or line drivers.
•
A master/slave network can have node numbers from 0...254. Each node must have a unique node address. Also, at
least 2 nodes must exist to define your link as a network, one master and one slave station being the two nodes.
DF1 slave
•
Using a controller as a slave station in a master/slave serial communication network.
•
When there are multiple slave stations on the network, link slave stations using modems or line drivers to the master.
When you have a single slave station on the network, you do not need a modem to connect the slave station to the
master. You can configure the control parameters for no handshaking. You can connect 2...255 nodes to a single link. In
DF1 slave mode, a controller uses DF1 half-duplex protocol.
•
One node is designated as the master and it controls who has access to the link. All the other nodes are slave stations
and must wait for permission from the master before transmitting.
User
•
Communication with ASCII devices.
•
This requires your program to use ASCII instructions to read and write data from and to an ASCII device.
DH-485 Communication with other DH-485 devices multi-master, token passing network allowing programming and peer-to-peer
messaging.