Hello. We have a machine with a Mitsubishi Q26UDHCPU PLC and a QJ71E71-100 Ethernet card. We use GXWorks 2. We use Kepware for data acquisition to/from the PLC. The PLC will randomly just stop communicating with Kepware. This issue has been ongoing for the last few years but has gone from once every two months to five times a shift. It'll come and go. One week it will do it frequently and then the next week it will work perfectly.
We get no errors when the communication stops. No errors on the Ethernet card and no errors on the PLC. The only thing that I have (very recently) noticed is that we get a generic warning on the processor in System Manager. I believe the warning is 10006.
What we have done to troubleshoot this so far: 1) changed the IP address of both HMI and PLC, 2) change the switch, 3) change to a completely different switch in a different part of the plant, 4) ran new Ethernet cables, 5) change the QJ71E71-100 with a brand new one, 6) installed a second QJ71E71-100 to create a private network for the HMI, 7) added channels to the Ethernet card in GXWorks2 for the HMI, Kepware and Melsoft Connection, all Unpassive, 8) changed the "Execute the process as the scan time proceeds" under PLC System tab of "PLC Parameter" from 10% to 15->30%.
The PLC stops pinging to my desktop when it stops communicating with Kepware. What I have noticed during this is that we have an HMI that is on the same switch with an IP address that is one number above the PLC. It maintains connection to the PLC always. Building off this, I found that plugging in my laptop to the same switch with an IP address on the same VLAN, it will ping to the laptop.
Does anyone have an idea why it keeps losing communication? Or what I can do to fix it. Our next step is to buy a new processor, the Q26UDEHCPU.