Verify Comm without having access to other PLC

[PierrePaulPaquet]

Hi,

I'm working on a project with an Allen-Bradley PLC, so we are using Studio5000. I have a bunch of things that communicate through ethernet/Ip and I verify the communication with every one of them. If I lose the comm, I latch something like an alarm depending on the situation.

Now here is my problem, we have some blowers that were made by an external company and are controlled by a Beijer X2 controller. I don't have any access to the controller, and the only information I can read/write are sent directly to some tags I created in Studio5000 (they are just basic tags, not even produced/consumed, I have no idea how it works). Now those tags are only updated when there is a change in the value in the Beijer X2 controller. This mean that I don't have a good way to verify if my communication is live. I can't do something like overwrite the value and if it doesn't change back, then I lost my comm because if the value doesn't change in the Beijer X2, then my overwritten value will stay even if my comm is good.

I usually use things like the connectionfaulted bit when I have a module with an eds, or GSV's when I use a generic ethernet module, but since the Beijer X2 controller doesn't work through a module, I don't see how I could use that.

I was thinking that maybe there is a way to use a MSG instruction, but I'm not very familiar with them.

All I have to work with is an IP Address.

Could I use something like a Generic Ethernet Module with None in the communication format and then use a GSV to get the EntryStatus? I've never tried this before so I don't know how it would work and I can't test it right now.

Any other suggestions?



Thanks.

 

[Ken Roach]

That's a great question !

The best way to affirm connectivity using this sort of system is to have the external message originator write a heartbeat or watchdog value to a tag in your controller periodically.

But of course since you don't have the option of changing the application, I would try verifying that the external device is at least connected to the network and running its EtherNet/IP stack.

I do that with MSG instructions that are addressed to the CIP Identity Object.

It can be as simple as doing a Get Attribute Single command to the Vendor Number attribute in the Identity Object. That is addressed as Class 1, Instance 1, Attribute 1.

Identity is a mandatory object for an EtherNet/IP device. If a device shows up in an RSLinx network browse, then it definitely has an Identity Object.

You can also do a List Identity command, which will return more than just the vendor number; there will be the vendor, device type, and device code for the product, as well as a text label and a firmware revision and a serial number. That's what the RSLinx Classic browse is doing.

 

[PierrePaulPaquet]

Thanks for the quick response and the suggestions.

I'll try them out when i come back from the holiday break.