I am struggling hard with a current issue. I have 7 CompactLogix connected to Ignition. This is the only PLC having complications. It was the first PLC connected to the network and the previous PLC programmer was guessing at best during startup. Their logic has three different programs with routines for each device in the field. So, the program is constantly jumping from routine to routine 26 devices on each program. I am probably just critical of this program and it most likely isn't the issue.
I set up an automatic email every time the PLC loses connection to Ignition, and I will get emails "randomly" that the connection has been broken.
The IT department has rebooted servers two weekends in a row. One weekend it was an uncontrolled crash. They do not shutdown Ignition softly prior to the server shutting down.
I made a save to the device configuration page of that PLC, in which I only changed the comment to assist in understanding what line the PLC is controlling. This caused the PLC connection to the gateway to break and only half the tags were populating when I browsed the device through the OPC connection path. I did not change anything else such as the name since obviously that would break every pathway. All I did was unconnected and reconnected the physical ethernet connection and the pathway was reconnected. Or so I thought....
Now, I do not know if this problem was pre-existing, and the events led to the finding of the problem. However, now I have noticed only the DINT or FLOAT values will alternate from good to bad. All the data is still being received by IT and production is continuing to run. I also have no idea why there are1,863 tags for the tag count? This PLC at most has 1200ish tags. Is there way in the configuration of this device the tag count would be off?
I cannot narrow down the problem to the PLC program processing "slowly", or the server restarts, or the scan rate set up on Ignition causing the tags to not be able to be scanned fast enough. I have tried changing the scan rate of those analog tags to 10 seconds and 3 seconds with no changes. The binary tags always appear good.
Any insight would be great. I appreciate the assistance and will be coming into work over the weekend when production is not running to dive into the issue further. Over thinker at heart and hate not knowing the exact cause!