Getting Comm status into RSlogix 5000

Hello All,

I am trying to get communications status of an Ethernet card into RSLogix 5000. I am using a 1756-L61 with a 1756-ENBT card.

Right now I am trying to a GSV command with a class name "Module". I'm not sure what attribute to use or what member of the structure to use. The help files aren't very clear to me.

Does anyone have any insight into how to accomplish what I am doing or maybe a better way to do it? All I want to do is trigger an alarm when I lose my communications link. I would think this should be fairly simple to do.

Any help that anyone could give would be greatly appreciated!

Thank you!

There are a handful of methods to perform connection status monitoring over EtherNet/IP. The GSV and the EntryStatus attribute of the Module object is one of them, and others involve CIP Generic MSG instructions.

Sometimes you don't have to go to those lengths and there are built-in Status tags that give you some information.

Explain exactly what you want to detect: you said "communications link".

Do you mean the actual Ethernet media Link ? That will use the TCP/IP Object and a CIP Generic message.

Do you mean a logical connection with an I/O module ? Use the GSV and the Module Object (search this Forum for multiple examples).

Do you mean a logical connection with a Produced Tag from another ControlLogix ? If you're using v16 or higher, you can configure these with Connection Status elements.

Do you mean a connection with a rack of I/O ? There are Status tags for things that have Rack connections (1756, 1734, and 1794, for example) that give you a single Bit per slot as a fault indication, but all Bits = 1 when the whole adapter connection is lost.

I basically want to detect if the card has an Ethernet Media Link. I was trying to set things up using GSV and the Entry Status Attribute. The Running signal should be all i need. The help files indicate that status I want is "Value 16#4000" of the integer but I'm not sure what that actually means?

I read that is Hex 4000 which is not correct. I am assuming what they really mean is bit 4 of a 16 bit word. Does that sound right? All I should need to do is use that bit to trigger a variable in my program.

These are all assumptions but it is where I was going with things. It wasn't working but before I went troubleshooting everything I wanted to get some advice to make sure I'm not out in left field.

Thanks!

Just because the ENBT has an EtherNet media link active, it doesn't mean it is still communicating with your remote ethernet devices.

Choose whichever of Ken's responses fits your needs.

And 16#4000 is 4000 Hex, or 0100_0000_0000_0000 in binary, which means bit 14 is on. I think also bits 0 to 11 could be on, and should be masked or ignored.

Ok, I see how the numbers shake out. I'm not sure what I was missing.

But it also seems that if I pull the ENET cable the status of the INT doesn't change as I thought it would.

But you are right, what I really want to know is if the module is communicating with any of my field devices. That is why I assumed that if the Link Active bit is on, then that should be all I need.

Is this status I'm looking at only the connection to the local ENET card and not the cards connection to the field?

It looks as though, reading all the other Entry Status value descriptions, it is only indicating that connection to the ENBT from the Controller is established, not that the ENBT has a valid outside world connection.

And a valid outside world connection could still be true, even though you are not communicating with the devices of interest, and certainly true if your network uses switches.

What devices are you communicating with ?

In general my requirement is an "Ethernet Communications Alarm". It is up to me to interpret that.

I have two Ethernet communication cards. One talks to 9 other Ethernet Cards and the second card talks to a dozen Ethernet IO devices (Valve blocks, VFDs and Point IO)

Thank you!

I'm trying to avoid looking at the status of all of them. All I care about about is whether each card has a connection to anything. Primarily is a physical connection actually made to the card.

As already said - the card may tell you it is physically connected to the network.And connected in this sense means just that, a physical connection is there.

But if you want to know that you have a "Connection", as in the passing of data, with a remote device, you will have to look at the individual "Connection Status" of each device.

The ENBTs do not "talk to" each other - they are simply "bridges", networking devices that translate Backplane network comms into EtherNet comms and vice-versa. They will be "talking" on the EtherNet network all the time, with switches, routers, DNS servers etc., etc.

Your data "Connection" for inter-PLC comms is controller to controller, and for remote I/O, is controller to I/O adaptor.

kupeyy said:

I'm trying to avoid looking at the status of all of them. All I care about about is whether each card has a connection to anything. Primarily is a physical connection actually made to the card.

Click to expand...

So as long as one card can talk to 1/9 other Ethernet devices and the other talks to 1/12 remote I/O that's OK?

I know the specification that you were given was sketchy, but as an end user I would hope to know when I've lost any communications not just all communications.

So thank you all for the suggestions. I setup 18 separate GSV commands to pull the status from each field device. With the correct mapping explained above I am able to trigger one alarm in my logic if any of the 16 devices lose connection.

That will work best. Thank you all!