Rockwell Automation 1756-DHRIO_DHRIOXT ControlLogix Data Highway Plus-Remote I/O Communication Interface Module - Manual (Page 170)

170 Rockwell Automation Publication 1756-UM514C-EN-P - June 2014
Appendix B Application Guidelines and Tips
Use Uncached Connections
The following figure illustrates the difference in messages per second available
with uncached connections for each DH+ baud rate.
Maintain PCCC Message
Sequences The 1756-DHRIO and 1756-DHRIOXT modules do not necessarily send
PCCC messages in the same order in which it receives them. To make sure of
proper sequences, wait for the PCCC response to the initial PCCC message
before you send another PCCC request.
0
10
Number of Nodes (that is number of messages)
1 2 3 4 5 6 7 8 9 10 11 12 13
20
30
40
230K
115K
57.6K
14 15
50
60
Messages per Second
70
80