Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

Cyclic-seletive archiving

Created by: rit03 at: 9/11/2006 6:27 PM (6 Replies)

Rating (0)

Thanks 0

7 Entries

9/11/2006 6:27 PM	Rate (0)
rit03 Silver Member Joined: 6/13/2006 Last visit: 2/11/2023 Posts: 341 Rating: (24)	I want to creat archive tag ("Int_Tag") which can be archive on cyclic-selective basis using event function instead of tag. When the function return true value the tag value start archiving. My requirement is as follows: When both of these tags namely "tag_1" and "tag_2" are true than "Int_Tag" should start archiving. I tried to use the event function but could not able to proceed as I could not able to make out from online help. Please give me a solution. regards rit03

Suggestion To thank Quote Answer

9/11/2006 6:42 PM	Rate (0)
Danielle Posts: 1275 Rating: (123)	The trigger function needs to return TRUE, or 1, to trigger the archiving. So your function would have to return something like the result of tag1 * tag2. How many tags will have their archiving triggered by that kind of function? Another way of doing that would be creating a third tag (tag3)which would be tag1 * tag2, and have tag3 trigger the archiving. But if you have several tags in that situation you'll end up with a lot of scripts, which is never good.
Danielle Posts: 1275 Rating: (123)
Suggestion To thank Quote Answer

9/11/2006 7:25 PM	Rate (0)
rit03 Silver Member Joined: 6/13/2006 Last visit: 2/11/2023 Posts: 341 Rating: (24)	Yeah I have 44 nos of tag to be archived on condition so I just want to know how to use Event function to do this instead of using tag which returns the result.

Suggestion To thank Quote Answer

9/11/2006 7:43 PM	Rate (0)
Danielle Posts: 1275 Rating: (123)	Like I said, the function event works like this: you name a function which returns TRUE when the archiving should start. The following came from the help: Start/Stop Events Events start and end process value archiving. Conditions which trigger an event may be linked to a tag or to scripts (C, VBS). In WinCC, events are differentiated as follows: Binary Event: Reacts to changes in a Boolean process tag. For example, turning on a motor may start archiving of a process value. Limit Value Event: Reacts to exceeding, falling short or reaching a limit value. Limit value changes may be in absolute or scaled numbers. For example, temperature fluctuations of more than 2% may trigger archiving. Time-controlled Event: Reacts to a fixed point in time period or passage of a time period after process value archiving has started. For example, a log is issued after each shift change. Function to Start Archiving int Function Name ( ); Description The function must return the value "0" (corresponds to FALSE) or "1" (corresponds to TRUE). Other values are not permissible. An archiving is triggered depending on archiving method and return value of the function. For cyclic archiving, archiving is always triggered if the return value of the function is "1". For acyclic archiving, archiving is always triggered if the return value has changed from the last function call. The first function call must return the value "1". The function may be assigned on the "Events" tab control of the "Process tag properties" dialog. Soyou'd need to create a function which would, as I said, return the result of tag1 * tag2. This function would be the event to trigger your archiving starts. That is assuming that for all the 44 situations you have the same tag1 and tag2. However if your event function has to be different for each of the 44 archive tags (tags 1 and 2 aren't always the same ones) I don't know how to help more...
Danielle Posts: 1275 Rating: (123)	Last edited by: Danielle at: 9/11/2006 7:52 PM
Suggestion To thank Quote Answer

9/12/2006 9:27 AM	Rate (0)
Salma Gold Member Joined: 9/27/2005 Last visit: 11/27/2007 Posts: 1398 Rating: (151)	Danielle has already explained how to use an Event Function. HOWEVERusing an event function will give you very, very bad performance. If you had 44 functions it would slow WinCC down dramatically !! The problem is because you cannot assign a poll rate for the event function. Therefore it will run every 500ms. Remember that scripts run synchronously so you will find that all your other project scripts are delayed because of the constant load on the script engine demanded by your event functions. Ideally this logic should be done in the PLC. If this is not possible then you should use a Global Action with a poll rate of 1second or preferably slower. You can't say you haven't been warned!

Suggestion To thank Quote Answer

9/12/2006 11:27 AM	Rate (0)
rit03 Silver Member Joined: 6/13/2006 Last visit: 2/11/2023 Posts: 341 Rating: (24)	Thanks for the information. I think the best idea as you suggest should be global action as I have to do 44 nos of archiving on condition. One more thing I want to clear, if the condition returns FALSE does it means it stops archiving if it so, than I can start and stop archiving using only one condition of archiving depending upon returns TRUE and FALSE . Hence , no need to creat another condition for stop archiving. Is this is the right way I am thinking?

Suggestion To thank Quote Answer

9/12/2006 11:37 AM	Rate (0)
Salma Gold Member Joined: 9/27/2005 Last visit: 11/27/2007 Posts: 1398 Rating: (151)	Sorry but I think it is when the event tag changes, and not when it goes to FALSE, that triggers the archive start or stop logging. So you will need to tags, one to control the start logging event, and the second tag to control the stop logging event. This FAQ might be useful too :http://support.automation.siemens.com/WW/view/en/71278

Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on