Hi all,
We have a control panel with a CompactLogix PLC and two Red Lion G310 HMIs. They communicate via a N-Tron 108-TX. One of the HMIs is installed on one of the panel door, in an air conditioned room. The other HMI is in the plant, about 120 feet away from the panel. Both HMI programs are identical.
The panel has been running a couple weeks every few months for the past year, and no issues were reported with the HMIs or the PLC.
Last week, the remote HMI started going “crazy”. I never had seen this behavior before. I've seen the typical dashes for the numeric values and black background on my motor labels (mine are white when the motor is stopped, green when is running, and red when is commanded to run but is not running). But this was different, there was a combination of dashes, black backgrounds and red backgrounds. I even noticed that before this situation some of the VFD speed labels were shown as zero, and also some temperature values. Also, the labels that are displayed only if the E-Stops are activated, were displayed. In other words, wrong tag values.
Also, after about an hour, some of the VFD speed signals from the PLC were set to zero. There were not a 4-20 mA signal meter nor a way to go online with the PLC at that moment.
If the panel was power cycled, the issue was cleared, but after a few minutes the remote HMI would start with the “craziness” and after an hour some of the PLC analog signals that control the VFDs speed were set to zero.
When I arrived to the plant, I disconnected the bad HMI, and the issues with the VFD signals was gone. Then, I updated the HMI firmware. I connected the HMI back to the network and the problem started in less than 15 minutes. I tried a couple more times with the same result. Then I decided to connect the HMI to the wireless router we use to connect the PLC to the panel, and also our phones to control the plant remotely. This has worked for the past 2 days.
I believe the cable for the remote HMI has noise, since the problem with the HMI starts when a specific set of motors start running. I grounded the Ethernet switch, but the problem persists.
I suspect the problem with the PLC was that the bad HMI forced zeros to the VFD speed values, overwriting the good values sent by the good HMI.
But now that I can prevent the PLC problem from happening, I'm wondering why the problem disappears when I connect the HMI to the router.
Thank you!
We have a control panel with a CompactLogix PLC and two Red Lion G310 HMIs. They communicate via a N-Tron 108-TX. One of the HMIs is installed on one of the panel door, in an air conditioned room. The other HMI is in the plant, about 120 feet away from the panel. Both HMI programs are identical.
The panel has been running a couple weeks every few months for the past year, and no issues were reported with the HMIs or the PLC.
Last week, the remote HMI started going “crazy”. I never had seen this behavior before. I've seen the typical dashes for the numeric values and black background on my motor labels (mine are white when the motor is stopped, green when is running, and red when is commanded to run but is not running). But this was different, there was a combination of dashes, black backgrounds and red backgrounds. I even noticed that before this situation some of the VFD speed labels were shown as zero, and also some temperature values. Also, the labels that are displayed only if the E-Stops are activated, were displayed. In other words, wrong tag values.
Also, after about an hour, some of the VFD speed signals from the PLC were set to zero. There were not a 4-20 mA signal meter nor a way to go online with the PLC at that moment.
If the panel was power cycled, the issue was cleared, but after a few minutes the remote HMI would start with the “craziness” and after an hour some of the PLC analog signals that control the VFDs speed were set to zero.
When I arrived to the plant, I disconnected the bad HMI, and the issues with the VFD signals was gone. Then, I updated the HMI firmware. I connected the HMI back to the network and the problem started in less than 15 minutes. I tried a couple more times with the same result. Then I decided to connect the HMI to the wireless router we use to connect the PLC to the panel, and also our phones to control the plant remotely. This has worked for the past 2 days.
I believe the cable for the remote HMI has noise, since the problem with the HMI starts when a specific set of motors start running. I grounded the Ethernet switch, but the problem persists.
I suspect the problem with the PLC was that the bad HMI forced zeros to the VFD speed values, overwriting the good values sent by the good HMI.
But now that I can prevent the PLC problem from happening, I'm wondering why the problem disappears when I connect the HMI to the router.
Thank you!
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