I need to connect Ignition to an Allen Bradley SLC504 on DH+.
To do this I’m going via a ControlLogix 1756-DHRIO module.
It all connects ok but for this particular PLC I need to read about 1200 tags and the diagnostics screen (Ignition 7.9) is showing this as 37 requests and the “Load Factor” is over 600%
Result: the comms keeps going bad.
I’m getting a Mean Response Time of around 176ms.
If in a test lab I put the same program in an SLC505 processor directly on Ethernet then the response time is about a 10th of that and the Load Factor is around 50%.
Can anyone advise what typical response times you’d get communicating to a Rockwell PLC via a CLX DHRIO card? Is 170ms expected? Or is that far too high? PINGing the CLX rack itself takes under 1ms so the delay must be on the DH+ side of things.