Property Transfer, Transaction overrun, overrun in 20 years 7 months
This message appears on a non cyclic basis over time. What does it mean? 20 years and 7 months???
We read/write OPC from a couple of Beijer panels using PLC Connect.
They also read data from a AC800M controller using Property Transfer.
Is there any possibility to adjust some parameters somewhere or is it just due to poor communication towards the Beijer panels?
We have tried adjusting the settings under Property Transfer but no success.
Voted best answer
The super light weight service acting as a "dual headed OPC client" in System 800xA we call the "Property Transfer " is unfortunately equipped with a number of (what I would say minor) faults.
- A standby provider may report garbage events
Simply disregard anything from a standby Property Transfer service provider; cycle it off/on to temporarily stop it from emitting garbage; however, the problem may reappear at next failover...
- Overrun is when speaker (OPC source of transfer) is speaking faster than the listener (the OPC destination of the transfer)
The only viable option is to increase the xxx time seen in Property Transfers enabled, maximum rate xxx milliseconds of the Property Transfer Definition aspect.
Still a failover will drive the overtaking Property Transfer service provider to issue a refresh (=request update from all groups) on the source side and post asynchronous write operations to the destination side, as fast as the "refresh updates" appear. Hence a failover (e.g. driven by an intentional reboot) of as few as 100 seldomly changing items in transfer may drive 100 writes in very rapid succession, in worst case, all of them, one by one since no optimization is made by Property Transfer to pack many more or less simultaneously received updates into fewer and larger write operations.
- Bad data from source will never be written to the destination, instead a cryptic message may be output - "Failed to convert to canonical datatype".
Property Transfer will attempt to use the Substitution Value defined in the Property Transfer Definition. A lack of a Substitution Value gives a "Failed to convert to canonical datatype" error.
Hence, such messages can be ignored if no substitution value has been defined. Really, Property Transfer should not even attempt to treat a null string.
- In late 5.1 era an error was corrected that (very rarely) could lead to a correct received value being written to the wrong destination at failover
Make sure you are on latest 5.1 rollup or 6.0.3, 6.1.0.
This was not a minor error, but at least, a by now corrected one.
Heed the distress messages a choked or failed Property Transfer destination may output to the [Workplace Structure]Web System Workplace:System Event List and/or Operator Message List. Property Transfer can only assume a "perfect" destination server able to keep up with whatever the source attempts to send and how fast it attempts to do so.
I'm not sure if the 20 years 7 months problem fall under item 1 or not, or else there is likely one more item/bullet to add to the above list.
Also, avoid enabling any of the other PT options like "Transfer all properties every ... seconds", "Retry failed write operations every xxx seconds" and "Minimum delay between write operatoins xxx seconds" (the two latter is set on the Special Configuration of the Property Transfer service group level) as they all risk to add burden to an overloaded destination server. However, a failed transfer of a seldomly changing property may be a disaster. It is hard to give advice fitting all. The Retry failed write... should have been made a setting local, per transferred property, not global for all.