New Ignition 8.1 gateway on the office side, VLAN 10, 10.10.5.20. I'm adding a ControlLogix on the plant side, a 1756-L72 with a 1756-EN2TR at 10.20.1.15 on VLAN 20, Allen-Bradley Logix driver, and the gateway log just says connection timed out.
From a laptop on VLAN 20 the PLC pings and Studio goes online without a murmur. From the Ignition server the ping times out. Every other device on VLAN 20 answers the server fine, the PanelView, a Kepware box.
IT ran a traceroute from the server. It reaches the VLAN 20 router hop and dies at the PLC, so they say routing is fine and it's my driver. I rebuilt the device connection and tried the legacy Logix driver, no luck. Maybe there's something in the EN2TR that blocks other subnets? What's different about the EN2TR that the PanelView on the same VLAN hasn't got?
Smallest test first. On the Ignition server, ping the EN2TR, and watch the PLC side while you do it. Can you get a SPAN port on VLAN 20, or a laptop with Wireshark on a tap next to the EN2TR? If the request arrives and no reply leaves, it isn't routing and it isn't the driver.
Got a SPAN on the VLAN 20 port. ICMP request from 10.10.5.20 arrives at the EN2TR. No reply at all. Instead the EN2TR sends out an ARP asking who has 10.10.5.20, on VLAN 20, over and over and over, and nobody answers it because that address isn't on this VLAN.
It's ARPing for an address on another subnet because it hasn't got a gateway. Same thing on our palletizer PLC. Studio 5000, controller organizer, right click the EN2TR, Properties, Port Configuration tab. Bet the Gateway Address box says 0.0.0.0.
> Bet the Gateway Address box says 0.0.0.0
It does. Whoever set this up gave it an IP and a mask and left the rest of the tab alone. IT told me the VLAN 20 gateway is .254, so I put 10.20.1.254 in and applied it and the module took it happily enough. Still no reply. Now its ARPing for .254 instead, and nobody answers that one either.
Then .254 doesn't exist on VLAN 20. Ask IT for the actual SVI address on VLAN 20, not what their standard says it should be. Ping .254 from your VLAN 20 laptop first. If that times out you've got your answer before they even reply.
Every plant has one PLC with the gateway box blank and one IT lad who says .254 without looking. Once the real address is in there it'll answer the first ping. Longer version on subnets and gateways here: https://plctr.com/advanced-plc-networking-and-communication-protocols/
.254 timed out from the VLAN 20 laptop too. IT went and looked properly, and the SVI on VLAN 20 is 10.20.1.1, the .254 thing is just their template for the office VLANs. Set 10.20.1.1 on the Port Configuration tab, applied, and Ignition went Connected before I got back to my desk. 400 tags at 1 s, clean.
So it was no default gateway on the EN2TR and then the wrong one. The Gateway Address box in Port Configuration fixed it. Nothing else was wrong, not the driver, not the firewall.
The PanelView and the Kepware box answered the server all along, so somebody filled their gateways in at some point I guess. Just not the PLC. No idea why. Cheers eddieb, carlh.
Glad it wasn't the driver. Write 10.20.1.1 on the panel door.