Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 135)

Publication 1785-UM012D-EN-P - July 2005
Communicating with Devices on a DH+ Link 9-3
For proper operation, terminate both ends of a DH+ link by using the
external resistors shipped with the programmable controller. Selecting either a
150
Ω or 82 Ω terminator determines how many devices you can connect on a
single DH+ link.
Configuring the Channel
for DH+ Communication Depending on the controller you are using, you can configure
these channels:
IMPORTANT
If you select the baud rate as 230.4 kbps, and you are using
the serial port or a PLC-5 coprocessor, use channel 2 for
better overall system performance.
If Your DH+ I/O Link Operates at Use this Resistor
Rating
230.4 kbps 82
Ω
57.6 kbps or 115.2 kbps 150
Ω
Controller Channels that Support DH+
PLC-5/11 1A
PLC-5/20 1A (fixed DH+), 1B
PLC-5/30
PLC-5/40L
PLC-5/60L
PLC-5/20E
PLC-5/40E
PLC-5/80E
1A, 1B
PLC-5/40
PLC-5/60
PLC-5/80
1A, 2A, 1B, 2B
IMPORTANT
To define the DH+ address and baud rate for channel 1A,
you must set switch assembly SW1 on the controller;
you cannot set this node address through the programming
software.