RSLinx Red X's, but it still works?!?

I've got a weird one here.

Just recently installed a VPN firewall that connects my office network to an Allen-Bradley PLC network. So here's what I can do:

- ping all the switches, and Ethernet devices (2 panel views, 1 ENBT card, 2 FLEX IO racks)
-bring up the card's webpages
-get online with the controller read/write code

Now here's where it gets weird.

When I open RSLinx Classic, all of my devices on my EthernetIP driver have red X's through them. However, when I expand my ENBT card, I can see the chassis, the processor and all the other cards with no problems(no red x's). Also when I right click on a Red X'ed Flex IO modules, I can see live Module Statistics from the Port Diagnostics tab.

So aside from the bold red X through the devices, everything seems to working alright. Am I missing something here?

Oh, when I go online in RSLogix5000 instead of Red X's i get yellow triangles in the RSLogix5000 software.

Does this same computer connect without the Red X when connected directly to the machine?

Sounds like it could be related to not having the most up to date EDS files.

Just a guess

when directly connected no x's

The only thing I can think of is port issues in the VPN, but you would think that would prevent ANY communication. Maybe RSLinx uses a different port for finding things then it does for communication?!?!?

I know I have seen this before and it is going to drive me crazy until I remember!

What is very likely happening is that your VPN is blocking the transmission of or responses to IP Broadcast packets.

The "EtherNet/IP" browser in RSLinx Classic and the driver in RSLinx Enterprise use a broadcast of the CIP "List Identity" request to perform a browse. Every device that hears that request is supposed to reply with its identity data, which is how RSLinx builds the network window.

If a device responds and is put into the RSWho network browse display, and then later stops responding (in your case, after the VPN was installed) then the red X will be placed over the icon.

Because ordinary RSLinx commands like "List Services" or "List Ports", which are part of the "drill down" mechanism, use normal TCP transport instead of a broadcast, they still work through the VPN.

If you were to delete your RSLinx EtherNet/IP driver and attempt to browse again, you would not see any of the devices on the far side of the VPN.

The simplest solution to this is to use the Ethernet Devices driver, where you manually enter the IP addresses of the network nodes. This does not use a broadcast, so it won't be affected by the broadcast blocking function of the VPN. You may have to append ":EIP" to the end of the IP address in the AB_ETH driver to force the driver to use exclusively TCP Port 44818 instead of attempting to first use TCP Port 2222 (the older A-B protocol for PLC-5E).

Now I will be able to sleep tonight! That is what I was think of, the word "broadcast" was on the tip of my tongue, Thanks Ken!

Hopefully this fixes the OP's problem.

Thanks Ken,

That's exactly what I did, but i didn't know why that worked! Thanks again.