I'll admit I know little about driven or leased tags as I've always used direct mode. This has generally been fine historically since I've been polling other RTUs with robust power/failover and metadata to indicate if values are bad quality.
However now I heavily poll devices in the field via Modbus, and these devices get their power from a distribution system. If these feeders and the aux transformers that power these controllers are de-energized, the devices lose power. If the devices lose power, the Modbus connections to Ignition go down. If the connections in Ignition go down, then we get lots of modbus poll errors cluttering up our logs.
Ideally I'd drive polling for these tags based on connectivity status for each device. E.g. for a UDT instance DeviceName, I'd poll only when [System]Gateway/Devices/[DeviceName]/Status is connected. However, Tag Groups appear not to allow parameterization of the driving expression (makes sense, since they are an object unrelated to a device or tag/instance). This makes me think I'd need to manually create a unique tag group for each device, something not feasible with hundreds of these devices.
Am I missing something here? How can I either...
Slow/stop polling when a device connection is offline
or....
Get rid of the awful clogging of my log files from bad modbus reads?