Professional OPC
Development Tools

logos

WriteMultipleValues writing order

More
11 May 2015 14:36 #3116 by support
OPC Write calls can contain multiple nodes/values to be written, and that's what we end up doing when you call WriteMultipleValues (we first split the arguments by the target server or other factors that demand splitting, but that's not your case I think).

OPC specs do not, however, prescribe that the order of elements in the array is the same in which the server should perform the Write.

Therefore the only way to achieve an ordered Write is to sequence it yourself, by making smaller calls (or even node by node, if that is what the requirement is), and only issue a next call when the first has completed.

There is also a special provision in OPC UA by which the server may indicate that the Write is returning the control to the caller, but the actual writing operation will be completed asynchronously later. If the server does this (probably not), then there wouldn't be any general way to achieve write ordering at all, because there is no completion indication.

Best regards
The following user(s) said Thank You: adid@contel.co.il

Please Log in or Create an account to join the conversation.

More
11 May 2015 10:19 #3115 by adid@contel.co.il
Hello,

when i am using WriteMultipleValues does the write done at the order of uaWriteValueArguments array ?
and if not there is way to call WriteMultipleValues with write at specific order ?

thank you,
Adi Damty

Please Log in or Create an account to join the conversation.

Moderators: support
Time to create page: 0.152 seconds

      

 Recommend this on Google