Rockwell Automation 1747-L5xx SLC 500 Modular Hardware Style User Manual - Manual (Page 208)

Publication 1747-UM011G-EN-P - June 2008
208 RS-232 Communication Interface
Channel O Configuration
The Baud, Parity, Stop Bits and Error Detection selections are identical
to the other DF1 drivers. Valid Node Addresses are 0...254, just like the
DF1 half-duplex drivers.
The primary advantage of using DF1 radio modem protocol for radio
modem networks is in transmission efficiency. Each read/write
transaction (command and reply) requires only one transmission by
the initiator (to send the command) and one transmission by the
responder (to return the reply). This minimizes the number of times
the radios need to key-up to transmit, which maximizes radio life and
minimizes radio power consumption. In contrast, DF1 half-duplex
protocol requires five transmissions for the DF1 master to complete a
read/write transaction with a DF1 slave - three by the master and two
by the slave.
The DF1 radio modem driver can be used in a pseudo master/slave
mode with any radio modems, as long as the designated master node
is the only node initiating MSG instructions, and as long as only one
MSG instruction is triggered at a time.
For modern serial radio modems that support full-duplex data port
buffering and radio transmission collision avoidance, the DF1 radio
modem driver can be used to set up a masterless peer-to-peer radio
network, where any node can initiate communication to any other
node at any time, as long as all of the nodes are within radio range so
that they receive each other’s transmissions.