Allen-Bradley 1756-DHRIO - DH+ Baud Rate Comparison; Using Cached Connections

Publication 1756-UM514B-EN-P - February 2003
Application Guidelines and Tips C-7
DH+ Baud Rate Comparison
Figure C.3 shows an example where a ControlLogix controller sends
messages to a PLC-5 via a 1756-DHRIO module. Performance
differences exist if the connections are cached or uncached.
Figure C.3
Using Cached Connections
Figure C.4 illustrates the difference in messages per second available
with cached connections for each DH+ baud rate.
Figure C.4
1756-DHRIO
PLC-5/60 processor
DH+ link
41283
ControlLogix controller
0
50
Number of Nodes (i.e. number of messages)
123 45678910111213
100
150
200
230K
115K
57.6K
14 15
250
300
Messages per Second
Version 5 of the 1756-DHRIO module added baud rates of 115.2K and 230.4K.