control logix msg slc read / write.

[danlhanson]

control logix msg slc read / write. in a 24 hour period i have 5600 successful and 60 failed. failed with ".err 656" and ".exterr 516" unconnected message timeout. i currently have 72 message instructions that are controlled (dn / er bit executes next msg). i am using clx L75, and en2t module. any suggestions on how to track down where the issue is, backplane, etc.

 

[djs]

Are you using serial, Ethernet, DH485 or DH+?

 

[danlhanson]

ethernet

 

[djs]

How loaded is your network? You might want to put a sniffer on it (WireShark). Highly loaded networks will occasionally drop packets.

 

[controlsdude]

Do a internet explorer on the Ethernet card of the IP in the address field. Go to diagnostics, if you CPU utilization is above 50% during heavy message traffic, then you got too much messaging going thru one Ethernet port.

Also, there is an system overhead time slice task % that you can play with that is usually set to 10%. You can bump it up to 30% without effecting PLC performance. Its under the controller properties, under the advance tab.

Another question I need to ask are you going past the connection limit of the processor with so many Ethernet messages?

Use the tool RSLogix Task Monitor tool, its under RSLogix5000 tools. See if your connection limit is exceeded.

I think on Contrologix L7x is 256 connections. I only saw this one time in my history of plc programming. If its the case you might have to put another processor in to divide the connections between them.

 

[danlhanson]

CPU Utilization.. the highest i have seen it is 3.5%,
My overhead time slice is set at 20%
CIP connections supported is 259, max i have seen at a time is 5, TCP connections supported is 128, max i have seen is 20
i do have RSLogix 5000 tool running, it looks good

I am starting to think that the problem may be on the other end, it is communicating to a Micrologix 1400 Series B processor. the read msg is 80 in length, and the write msg is 10 in length. i am starting to think that the 1400 may be locking up or not responding. the combination of the reads/writes equates to 15 msg's/per minute per micro 1400. anyone have any experience with that
thanks for assistance

 

[controlsdude]

review these AB or Rockwell pdfs maybe shed some light on your problem. Just google them should take you to Rockwell site to download.
INTEGRATIONWITHCONTROLLOGIX PROGRAMMABLE AUTOMATIONCONTROLLERS (PACS)USINGETHERNET/IP
This below PDF can give you understanding on particular comms with micrologix, some sections you should read that pertains to the micrologix/slc type comms.
Rockwell Automation Publication 1756-UM001M-EN-P - February 2012