Trimming junk from a string

[PLCwannabe]

  What is the easiest way to trim junk from the back end of a string? I'm able to trim the front end with The Get Sub-String (STRSUB) instruction, but the end is harder to trim because the strings are a variable lenght. eg.  { ...current: "All Clear"...}  The string always begins with the same 15 characters, but the message varies depending on the current conditions. So right now I end up with                               
         "All Clear"...}  and I want to remove the periods and the curly brace at the end.

[franji1]

         "All Clear"...}  and I want to remove the periods and the curly brace at the end.

Show a screen shot of a sample string in Data View in "8 Hex/ASCII" text format.

I am guessing there's CR/LF and something else in there, and you will need to use STRFIND and STRTRUNC, but we need to understand the delimiters (again, probably CR/LF, but need to make sure, hence the Data View screen shot).

[PLCwannabe]

Ok.

[franji1]

It's JSON!  IIOT likes JSON records.  Do-more PLCs speak JSON!

Basically, you want to do a JSONPARSE for the field "current" whose data is a string (the field names are always in double quotes, but the data in a JSON record can be numeric or string, "current" is a string)

See the attached screen shot.

Try it and turn on Ladder Status to crack the return results code properly.  The details on a successful parse is in the Help Topic for JSONPARSE DMD0454

[franji1]

Look at Alarm1SS1 in the JSON Pretty Print tool (Debug->JSON Pretty Print).

Turn on the COLOR CODED NESTING checkbox

[franji1]

You may want to do a STRTRIM on the result in SL0 to remove the trailing spaces.  I wrote a small program to do your sample and it worked.  See the attached screen shot.

[PLCwannabe]

Ok, now I get it, I need to do an additional parsing operation. Thanks.

[franji1]

Ok, now I get it, I need to do an additional parsing operation. Thanks.

I think you just need to replace whatever parsing you have with JSONPARSE (no "additional" parsing necessary).  The device is returning a JSON record and Do-more has the JSON parsing algorithm in that instruction.  So take the string being read from the device and feed it in JSONPARSE - it handles any/all white space in the input string.  Unless there's some other overhead wrapped around the data being returned from your device?