Move a String in Step7

Hi,

I am trying to move a string from one data block to another in ladder, overwriting a string of the same size that is already there.

I have tried using BLKMOV (SFC20) and FILL (SFC21) but can't get it to work. When The block is enabled I don't get an error but if I open up the data block that I am trying to move the string into and turn on monitoring I still see the default value.

Source String is:
DB100.0.0, SMS_WaterAmber, STRING[160],'WFD Water Level Amber'

Destination is:
DB8.56.0, Message, STRING[160], 'Testing123'

Any help you could give me with this would me much appreciated.

You cannot monitor a string in a DB.
Use a vat table and monitor a list of chars in the destination DB.

What parameters are you passing to SFC20 ?

based on my experience that only allows monitoring characters and even then it is not suitable for more than some 10-15 characters. same is with DB, you can monitor only first string (or part of it).

Thanks for the reply.

I am passing dbsource.SMS_WaterAmber into the source and dbtarget.Message into the destination.

When I hover over them the tooltip gives DB100.0.0/"dbsource".SMS_WaterAmber/access width 162 bytes
And the equivalent for the destination.


I have found the vat table (I think) but have not used it before, so I am not sure how to monitor a string with it.

Have a look at this example, select char for the type of variable:

http://www.plctalk.net/qanda/showpost.php?p=303275&postcount=6

Thank you very much!

That enabled me to confirm that my strings are transferring correctly.

Thank you again.