Hi.
I have Modbus RTU over TCP device. Its status is connected and always was. But sometimes tags go to bad quality and remain so until device will restart from device configuration page Edit->Save Changes. Can you help me to diagnose this issue?
I have a similar situation.
Modbus TCP device connected using the Modbus TCP driver. Device shows connected, gateway quick client can read good data from the Modbus registers, yet the majority of my tags are in bad quality. I have two tags that come back with Good quality. I have done the following:
Consideration: This is a PQM with multiple device connections at this time. Using Modbus Poll, I have not seen any loss is data traffic.
Verified that the Scan Class assigned is a scan class in the system
Verified that the tag path is correct when using tag parameters assigned
Verified that the device is connected and allows for multiple connections (Two in Ignition, one original and one for testing, and one from Modbus Poll to test modbus data output from the device)
Verified that the Ignition OPC Quick Client can poll the device and return a good value
Assigned the OPC Item Path using the OPC browser.
Researched modbus register type assigned in the device addresses to the Tag type. This does not seem to be a factor as I have Floats assigned with Floats and these tags are in Bad Quality
After all of this, I have 2 out of 24 tags in Good quality. Any advise?
Update Found that this was a device issue. The device allows multiple connections, but once the registers were being polled by the first connection, those registers would return bad quality on the second connection. Any registers that were not in use would return with good quality.
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Can you identify the device/version for posterity?
Device is a Triacta Powerhawk 6412-120V-3P-08 Power Meter FW 2.04 Build 1215
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I have something like this going on with a couple AB PLC's. One is a CompactLogix and another a ControlLogix. Different firmware versions, but both going to a 7.9 gateway. seemingly random, they will loose comms on SCADA and it shows connected in the Gateway. Disabling/re-enabling the devices brings it back. So like a blip in comms that doesn't fully resolved until the connection is refreshed. I have some co-workers that experience similar issues in various setups. Is this something fixed in 8.1 or a newer version of the Logix driver?
Doesn't sound familiar. There was a bug that took a while to figure out where it would get stuck in the "Idle" state, but I don't remember anything where it would report as connected. If you want to troubleshoot you can call support while it's happening, or even before, so they can get logs and maybe set up a rolling Wireshark capture.
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Will try and call when it's in that state. It's so infrequent, that wireshark may be running for several months before it happens again.
Yeah, but if you set up a ring buffer then it's okay to run it for several months. You end up with a fixed size set of capture files that don't exceed a configurable file size limit.
edit: plus you'd want to properly filter so only traffic to/from those IPs are captured. Reduce the amount of data even further. Support should know how to do this.
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Ah. Good to know. Thanks!