ASCii Bad string flush

Tlogix · Jul 9, 2013

Im wondering if any one has had the privilege of getting in a Ascii string thats to long or corrupted and how to get rid of it or flush it out?

Ken Roach · Jul 9, 2013

Well, sure, but I just scrub it with a wire brush.

What sort of controller are you using ?

Tlogix · Jul 9, 2013

ML 1400
This is what the string looks like I get it in and some times the controller will give me a error some times my ladder will stop executing without a error .

,318.5,\CDN\A9\8A^Y1\E9\82j^J$GPGGA,001650,4810.9808,N,09742.1038,W,2,07,1.4,323.2, ,-24.8,M, ,

Tlogix · Jul 9, 2013

Tried the wire brush thing just scratched up the screen

BryanG · Jul 9, 2013

The $GGA sentence normally finishes with a check sum. From what I remember you have to XOR each character in the sentence, then if your calculated checksum doesn't equal the $GGA check sum you can throw away the data. I have done this in C on an embedded Linux computer but not in a PLC. Before that I also checked that the characters received were alphanumeric characters, spaces or punctuation.

(8{)} ( .) · Jul 9, 2013

Groan. Parsing in ladder. I feel sorry for you.

Can you set your termination character to ","
Then try to sort out what's going on with the individual strings.

Good Luck,

(8{)}

.)
(Yosi)

Doug-P · Jul 10, 2013

Based on PLC-5 operations I can think of two ways.

Create and maintain another string with a value of 82 spaces, or your character of choice. Copy this blank string into the bad one.
Set the length parameter of the bad string to zero (CLR ST9:X.LEN). The data still resides in the string but any instructions which reference the string will assume it has no data because of the length parameter.

YMMV

ASCii Bad string flush

Tlogix

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(8{)} ( .)

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