Jimmah! (Customer) asked a question.
Help with Detecting Loss of Panel Communications
Hi everyone and happy new year!
I am working on a project that is using a C-more HMI touchscreen, model EA9-T10WCL. In my application, it is important for the panel operator to know if the panel has lost communications with a single PLC that feeds it information.
- I have contacted support previously and learned that there is no internal tag that I can use to determine this event.
- If I unplug the ethernet cable from the back of the device, I will eventually see an error message across the top of the screen indicating a communications timeout.
I have used other HMI devices and software in the past that support event reporting/tag based on good/bad communication link with the data source. Is there any sort of workaround for this device? I honestly cannot believe that they don't provide a system tag that reflects link status and I probably won't use this OEM in the future as this is an important and curiously absent feature.
Thanks,
Jim
"I have contacted support previously and learned that there is no internal tag that I can use to determine this event."
This is not correct. Check Help Topic CM321.
Go to: Setup->PLC<->Panel->PLC Error.
The internal discrete bit in this menu flashes at the same rate as the banner. The Error code provides a Word for the different errors.
If you want to have a "latching" light that doesn't blink with the banner, you can use the event manager to set a comms fault bit when the PLC Error State bit initially turns on. This bit could then be reset from the PLC once comms are re-established. If you want something beyond just a simple error (comms or otherwise), you can use the PLC Error Code Value and the Event Manager to trigger indicators specific to each fault type.
+1 @RBPLC (Customer)
Here is a post that will discuss the PLC<->Panel communication.
https://accautomation.ca/c-more-ea9-hmi-series-panel-to-plc-and-plc-to-panel-settings/
I hope this helps you out.
Regards,
Garry
https://accautomation.ca/series/c-more-hmi-series-panel/
I do not think you understood what he is suggesting. If you lost communications to your PLC, then the PLC can not receive any error to begin. Nor could the PLC inform the operator via the HMI display because.... well there is no communications.
With a system tag, at least you could indicate an error on the screen of the HMI instead of relying on a banner at the top that can be cryptic. If I am on a screen, it may be imperative that the operator is complexly aware that the values displayed may be outdated and not rely on them to see a flashing banner that may be displaying multiple panels with COMM errors.
There should absolutely be a system HMI tag that can be used to display warnings. You should be able to disable the banner altogether which is another needed feature as it makes the top of the HMI unusable for essential display.
In the panel manager, need a block where you can enter a unique system tag name that will represent loss of communications to that panel. Is a fairly simple fix.
Just when I thought I was the only one with this problem.
I am using the good communication toggle to trigger an output on my PLC to run an audible alarm if I lose communication to my HMI but there should definitely be something on the HMI that show's the values aren't being updated and there should be something to disable the banner as the above customer.
If automation direct decide's to fix this issue make sure we can set a time before HMI show a comm. alarm because sometimes communication comes right back up.
Your help is appreciated.
They already have a comm alarm delay feature enable when you setup the parameters for a new panel. That is set in the panel manager in the time out and number of retries. All they need to do now is in that same screen, simply have a spot where you can add a system tag that is set when loss of comms are detected. Possibly a second box to disable showing the comm loss on the banner screen.
This is really a critical requirement in a panel. With some items being life safety type of information, you want operators to absolutely know when the data being displayed may not be valid. Relying on them to read a small banner at the top is not good enough. Particularly if you have many PLCs connected to same panel.
I too have set up PLC to check but that is not that useful if the HMI is in a separate building using TCP/IP.. Thank for responding as I thought maybe I was missing something on such an essential feature.
Tupac, thanks for your post. Obviously you are being faced with the same need that I had. It's odd that the OEM doesn't provide a system tag for this and it's kinda wild that this HMI, as great as it is, lacks this simple feature.
I'm not sure what you guys keep talking about. Use the either the PLC Error bit or PLC Error code and then use the Event Manager to either change screens to one that says you have a comms error or have a message box pop up that says you have a comms error.
Been there done that.
Maybe it's inexperience( very possible) but that doesn't work very well for me first of all using time out and number of retries to set a time delay is erratic and those 2 tag's you mentioned are not dedicated just to comm loss.
And that does not solve the issue of being able to disable the banner which hides information.
But that being said I am fairly new at this and maybe I am missing something.
The original post didn't mention anything about the banner. The banner cannot be disabled. I suspect that is by design to force resolution of that issue. May not be a great approach but that's how it is. Concerning the error tags, one is a bit the other is a Word. The Word gives the specific fault types. Pick the fault code you need and use that to trigger the Event Manager action indicating loss of comms.
Thank you . I knew I was missing something. I did not know I could get that specific fault displayed.
As for the banner I guess if you have a comm. error the info displayed is not valid anyway.