Allen-Bradley 1756-DHRIO - Remote I;O Performance: Controllogix Vs. PLC-5

Publication 1756-UM514B-EN-P - February 2003
C-6 Application Guidelines and Tips
Remote I/O Performance:
ControlLogix vs. PLC-5
In Figure C.1, block transfer write messages are sent from a
ControlLogix controller (via the 1756-DHRIO module) to a 1771-DCM
over cached remote I/O connections.
Figure C.1
Figure C.2 illustrates the differences between using cached remote I/O
connections with the 1771-DCM module and using PLC-5 connections
with the 1771-DCM module.
Figure C.2
1756-DHRIO
1771 Chassis containing:
PLC-5/60 processor
1771-DCM module
Remote I/O
41283
ControlLogix controller
0
20
Number of Nodes per Block Transfer Write Messages
1 2 3 4 5 6 7 8 9 10 11 12 13
230K Cached
40
60
80
115K Cached
57.6K Cached
230K Cached
115K Cached
57.6K Cached
14 15
100
120
Block Transfer Write
Messages per Second
All 15 Block Transfer Write messages were on one channel.
Each Block Transfer Write message was 40 words in size.