# Siemens Profinet **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [January 31, 2024, 9:39am UTC](https://forum.inductiveautomation.com/t/siemens-profinet/85006 "2024-01-31T09:39:39Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![pick](https://avatars.discourse-cdn.com/v4/letter/p/9de0a6/32.png) [@pick](https://forum.inductiveautomation.com/u/pick)\ **Post date:** [January 31, 2024, 9:39am UTC](https://forum.inductiveautomation.com/t/siemens-profinet/85006/1 "2024-01-31T09:39:39Z")
Hello, I have a com between Ignition OPC UA server and Siemmens PLC 1200 and 300. On PLC side there is a DB with tags: ![DB](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/4/b41cf9e5483204cdc570b12cc93ed540104ffe83.png) And on Ignition side the same tags: ![dbignitionPNG](https://us1.discourse-cdn.com/inductiveautomation/original/3X/0/4/045f2375af0827b882e40e1dde7b0121a4d508dc.png) A transaction group on the tag "CW\_PLC\_MES" = 180 record the value of the tag "Status". The PLC write 180 to "CW\_PLC\_MES" just after writing 1 or 2 to "Status" (the initial value is 0). But some time Ignition doesn't get the update value of the "Status" and record the old value 0. I made a trace on PLC and I am sure "Status" is always egal to 1 or 2 when "CW\_PLC\_MES" egal 180. Siemens support told me the value of "Status" is immediately available and I shoudl better check the Supervision. I put a 200ms time delay on PLC side between the writing of "Status" and "CW\_PLC\_MES" and it work always work fine. Would it be possible the information from the PLC is not send in one time, and Ignition received one frame of data regarding the "CW\_PLC\_MES" and slightly after the frame of data regarding the "Status"? ---
**Author:** ![victordcq](https://avatars.discourse-cdn.com/v4/letter/v/f6c823/32.png) [@victordcq](https://forum.inductiveautomation.com/u/victordcq)\ **Post date:** [January 31, 2024, 10:06am UTC](https://forum.inductiveautomation.com/t/siemens-profinet/85006/2 "2024-01-31T10:06:54Z")
Different tags dont really update at the same time, i found this on the forum > [@OPC Tags not updating at the same time?](https://forum.inductiveautomation.com/t/opc-tags-not-updating-at-the-same-time/23274/3): > > This is not true. When tags are subscribed to OPC items, the OPC server makes a best effort to deliver the data at the pace indicated in the scan class, but makes no guarantee. No guarantees for order of delivery, either. Tag change events can and do start executing right away, while other tags on the scan class are still updating, if updating at all at that time. In your case, I would have a tag subscribed to the PLC trigger item as you describe, with tag change script, but I would use sys… ---
**Author:** ![pick](https://avatars.discourse-cdn.com/v4/letter/p/9de0a6/32.png) [@pick](https://forum.inductiveautomation.com/u/pick)\ **Post date:** [January 31, 2024, 10:16am UTC](https://forum.inductiveautomation.com/t/siemens-profinet/85006/3 "2024-01-31T10:16:23Z")
I missed this one thanks