PLC to kepware connectivity

[jensc]

Hello,

I am quite new to using Kepware so sorry if there is a super obvious answer to this question.

What are some ways a PLC can know that it has lost connection to Kepware?

In one of my projects we created a handshake between Thingworx and the PLC to ensure that the PLC would know that the data had been saved on the Thingworx side.

I also read about some OPC UA status codes that should be sent if the connection is lost.

Is this what should be used?

I have tried to find some information about this on google but haven't really had much luck, so any help would be highly appreciated.

Thanks,

Jens

[PaiChung]

Not the great expert here, but Kepware will basically fail to retrieve data from the PLC and that is what you could use to detect disconnect from the data source, then if Kepware is disconnected from Thingworx, that is also detected.

[jensc]

Hello @PaiChung,

Yeah, it seems like the easiest thing is to check the status of the properties, if they are good or not. Or if the PLC needs to know that the data has been saved, do a handshake.

As it is Kepware that is reading from the PLC, I suppose it would be close to impossible for the PLC to be able to know if Kepware can read the values or not...

Thanks for the clarification!

Regards,

Jens

[cmorehead · Accepted solution]

@jensc 

There is a device level system tag called "_Error" which can be used to detect when a device has become disconnected. Here is a link to the page in the KEPServerEX manual that covers the system tag use:

https://www.kepware.com/getattachment/e1943820-ef3c-4932-b055-4ef2a80ab863/kepserverex-manual.pdf#page=128

Thanks,

*Chris

[SlidingDownhill]

I use those _ERROR tags and can verify they work very effectively.  

[jensc]

Hello,

This can for sure be useful to notice a general issue with the connection to a device.

I'll have to check it out and try it out!

Thanks,

Jens