Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

FC4 delete

Created by: dave_t at: 5/4/2007 4:41 PM (3 Replies)

Rating (0)

Thanks 0

4 Entries

5/4/2007 4:41 PM	Rate (0)
dave_t Posts: 11 Rating: (0)	Anybody, Was looking for some help with the IEC function FC4 delete strings. I want to use this function to clear a string buffer I have created but can not seem to get it to work successfully. I think I am missing something in relation to the L and P characters. I understand that the L character is the length of the string you want to delete and the P character is the start address. Appreciate any help. dave_t
dave_t Posts: 11 Rating: (0)
Suggestion To thank Quote Answer

5/5/2007 4:52 PM	Rate (0)
Late Platinum Expert Joined: 1/7/2006 Last visit: 2/16/2023 Posts: 2705 Rating: (311)	Dear DAve, A string in STEP7 is built up by two leading characters L and P and the string itself. If you declare a string with a length of 4 for example, then you need 6 byte to hold the string. The Length (L) is then holding 4 and the Pointer (P) is holding the actuall length of the string. Example: The string "Yes" is placed then in the 4 character string as following: Number 4, Number 3, Character "Y", Character "e", Character "s" and Character ? When you work with functions that are working with strings, then you have no trouble (exception is working with TEMPs).
	I hope that the answer will help, if you have still questions, don't hesitate to ask me. All the best, Late Never say never, think in solutions, not in trouble......
Suggestion To thank Quote Answer

5/8/2007 12:04 PM	Rate (0)
dave_t Posts: 11 Rating: (0)	To Late, Thank you for the response. I am aware of the L and P parameters. However with this particular function there still seems to be a few conditions particularly related to the values entered for L and P that cause the string to be returned into the buffer. In your example if you were to enter 3 for L and 1 for P this function should then delete the string YES. However everytime I examine the buffer the string is returned. Best Regards, Dave.
dave_t Posts: 11 Rating: (0)
Suggestion To thank Quote Answer

4/30/2012 10:53 AM	Rate (0)
Elonen Bronze Member Joined: 4/11/2012 Last visit: 8/1/2022 Posts: 176 Rating: (32)	I have this same problem, I just made a topic of it here, with some additional information: /tf/WW/en/Posts/73379#top

Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on