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OpcUa "BadTooManyOperations"

Posted: 05 Apr 2017, 13:48
by Se├Ęk

im working on a visualization on a PowerPanel (PP500) from Siemens. There is a programm on the sps communicating with the Opc Server. I do get a connection but when i wanna read out the variables there occurs an error which says "BadTooManyOperations" there are many variables on the server... may that cause the problem? on some variables it works... on the most of them not..i am no upcua expert :/ i dont know what to do :(

Re: OpcUa "BadTooManyOperations"

Posted: 22 Apr 2017, 18:31
by Support Team

an OPC UA Server on a "weak" machine can limit the number of tags that can be used in a single operation or call. Especially embedded devices with slow CPU and limited memory size can use this feature to protect themselves against powerful (and rude) Clients. A good UA Client should read out the UA Server's operational limits first and adopt to them. If the Server has an operational limit of e.g. 100 Nodes per Read operation, the Client should respect this and break down the Read for 1000 tags into 10 packages of 100 and do 10 Reads in a row. Similar limits may exsist for the Subscription, the Write and the Browse operation.

That said it is no problem that the server may have several thousands of variables, it just allows to only Read 100 of them at a time. You just need to break down the read operation into smaller packages to avoid overloading the Server.