User manual

Publication 1768-UM001C-EN-P - November 2007
34 Communicate over Networks
Serial Network
Communication
The 1768 CompactLogix controllers have a built-in RS-232 serial port that you
can configure.
DF1 Modes for Logix5000 Controllers
IMPORTANT
Limit the length of serial (RS-232) cables to 15.2 m (50 ft).
Mode Functions
DF1
Point-to-Point
Communication between a controller and one other
DF1-protocol-compatible device.
This is the Default System mode. Default parameters are:
• Communication Rate: 19,200 bps.
• 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 a controller through its serial port.
DF1 Master • 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, for your link to be a
network, it must consist of one master and one slave station.
DF1 Slave • A controller to operate as a slave station in a master/slave serial
communication network.
• When there are multiple slave stations on the network, link slave
stations by 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 controls who has access to
the link. All of the other nodes are slave stations and must wait for
permission from the master before transmitting.
DF1 Radio
Modem
• Compatible with SLC 500 and MicroLogix 1500 controllers.
• This mode supports Master and Slave, and Store and Forward modes.
User (channel
0 only)
• 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.
• This multi-master, token-passing network permits programming and
peer-to-peer messaging.