Custom protocol OPC driver with device history replay issue


I have recently developed a driver for our custom protocol (TCP based). The driver and the device (PLC) support history rewind feature. I use the Value timestamp for historization. I noticed from the gw console, that there are a lot of exceptions due to overlaping data. That’s OK, it’s only in the console and only happens on reconnect. However, because the store and forward mechanism stores batches of records in a transaction, the transaction that partly overlaps with old data in the database and partly holds data that are missing, fails because of the overlaping data. The result is, that a few records that are processed within that transaction do not make it to the database resulting in a gap.

Any suggestions on how to solve this?

Using Ignition v. 7.7


OK, this was due to the fact that I was using EasyChart which displays bad quality values as gaps. When I changed to Chart and chose to ignore bad quality values all is fine.