As i seen it seems though i am unable to read certain items from my PLC (siemens S71200). I have made no changes and this keeps popping up randomly. From a previous thread opened here their solution was to WAIT until it goes away. What is this error and why does it keep reappearing as if its a read glitch? I am unable to fix this. A solution that as fixed this in the past is by changing the DB i’m reading in the PLC. However this solution is not viable as i cannot keeping going back to site to reprogram a DB number
The problem is that i don’t know what the error is referencing. The moment this error occurs, i lose communication to half of PLC. no changes has been made to any string. The latest updates that were made (day before) were working ( I added extra bits to a byte that was using 3/7 bits). When i got back to the SCADA, the comms where not working (on certain tags) and that is the only error on the logs.
The comms i lose are random, which makes no sense Eg. i made a test bit at the very beginning (tag path - [S71200PLC]Qx0.1) to test my read/write. this connection is also down( note i can turn on the output even though the tag says bad which still tells me something on the ignition gatway/OPC is unable to read) . All of the tags that loses comms either say Bad or Uncertain value. Later some of the bad tags go healty/good again.
Where/ how do i find the item the error is referencing
This looks like a driver bug. Call support and they’ll want your logs and a list of all the tags you have configured from that device and any other info you might have about how to make this happen if it’s only intermittent.
