Gateway OPC Client Stops Reading While Connected

Ignition
,
1

I’m having a periodic issue that has become an increasing concern as I’m approaching the finishing touches of my project.

I have my gateway running as an OPC client with a Siemens S7-1500 running on PLCSIM Advanced as the OPC server. Everything happy and working, going through the bug finding phase of my HMI/PLC handshaking. I left my operation running and flipped to a browser to read up on something. I flipped back to my HMI and I was confused with what I was seeing. It was essentially a dropout of my HMI visualization. I thought nothing of it the first time, reset my PLCSIM, back to bug finding.

Today I’ve had it happen again and now I realize there’s an actual issue. Essentially my gateway is maintaining connectivity with the OPC server but not reading or writing anymore. I don’t get any connectivity problems on my HMI (I have a system bit monitoring connection with PLC, maintains “Connected”). I flip over to my gateway and check the connection, and it’s “connected”.

I opened up my TIA Portal, checked outputs, they are on as they should be. Opened up UAExpert to check with third party, and it’s reading the PLC OPC tags correctly. My HMI is essentially dead in the water, and when trying to interact with the HMI to take control of the machine, I get a bunch of conflicting things, where some bits are reading correctly and others aren’t reading at all.

The only sure way to fix this is to disable my gateway client connection, re-enable and boom it’s back to normal.

What the heck is going on? I have experienced this probably 3-4 times over the course of a month. It’s not an everyday problem, it’s a randomly occurring event that’s very recognizable. Again, I’m running PLCSIM Advanced, which is a little different than a physical setup, but my UAExpert has no problems with this. My client isn’t timing out because it’s remaining connected. It’s like it just stops reading and writing correctly, and nothing seems to fix that except a connection reset, which is unacceptable. Any thoughts would be appreciated.

The pictures below show this. MECH PUMP/BOOSTER PUMP on PLC outputs are true, UAExpert sees this, HMI not showing true for the bottom right pumps. HMI showing “Connected’ in the top banner, left side.

826_GATEWAY
826_GATEWAY1918×1062 130 KB

826_PLC
826_PLC1917×1197 271 KB

826_HMI
826_HMI1918×1198 385 KB

826_UAE
826_UAE1918×1198 181 KB

2

We'll need your log files as a starting point.

If/when this happens again it's also worth figuring out if it's just the tags on the screen that aren't updating, or if they aren't updated in the Designer's Tag Browser as well.

If writes stop working too that's interesting... is there an error? Do they fail from the Designer Tag Browser? From the OPC Quick Client?

1 Like
3

Thanks Kevin, I’ll remember to do this when it happens again. Yes it’s also the writing function that stops working. I have a PLCSIM popup on Ignition where I’m toggling "physical inputs” to test the machine. I press these check boxes and I see it trying to write, but it will reset back to false (it’s bi-directional). So it’s trying to write, but not able to lock in that data transfer.

I’ll take more pictures the next time it happens.

4

Hi Kevin,

Happened again this morning. Here’s an image of my gateway log, which appears to show a license timeout, and re-enabling. It says it succeeded, which may be true, but I’m not able to r/w to it without resetting like I described before.

image
image1418×677 51.6 KB

5

I think a rolling Wireshark capture is going to be necessary...

In those logs we lost the connection, reconnected, presumably re-created subscriptions etc... and now the server appears to not respond or send data, but there's nothing to prove or disprove that without a capture.

Support can help you get a capture setup that is filtered for just this host/IP and rolls over between a number of files so you can leave it running.

1 Like
6

Thanks, I’ll get a ticket started