Cognex barcode data comparison in PLC

[drbitboy]

SUB Print.ST16[30].Data[1] COGNEX:I.Result[0] diff

EQU diff 48 SUB Print.ST16[30].Data[2] COGNEX:I.Result[1] diff

EQU diff 48 SUB Print.ST16[31].Data[1] COGNEX:I.Result[2] diff

EQU diff 48 SUB Print.ST16[31].Data[2] COGNEX:I.Result[3] diff

EQU diff 48 OTE BarcodeMatches

​

In Logix, that could all be on one rung.

Caveats/Assumptions

• diff is a SINT tag
• BarcodeMatches is a Boolean, with a value of True if the barcode matches the Print.ST16[30]+Print.ST16[31] pair.
• Print.ST16 is an array of strings
  • So Print.ST16[030] is not 10
    • but is '10' i.e.
      • a string
      • Print.ST16[30].LEN is 2
      • Print.ST16[30].DATA[1] is 49 (SINT) and '1' (ASCII character)
      • Print.ST16[30].DATA[2] is 48 (SINT) and '0' (ASCII character)
• COGNEX:I.Result is an array of SINTs, with integer values 0 though 9, and not ASCII characters, where the SINT value 1 represents the ASCII character '1' (SINT 49)

 

[cwal61]

COGNEX:I.ResultData[0] = 1
COGNEX:I.ResultData[1] = 0
COGNEX:I.ResultData[2] = 2
COGNEX:I.ResultData[3] = 5

Cognex Camera Results are sent to the PLC as ASCII values. 4 compares of the .DATA[n] in series to an OTE will show if all are true.

EQU COGNEX:I.ResultData[0] Print.ST16[30].DATA[0] EQU COGNEX:I.ResultData[1] Print.ST16[30].DATA[1] EQU COGNEX:I.ResultData[2] Print.ST16[31].DATA[0] EQU COGNEX:I.ResultData[3] Print.ST16[31].DATA[1] OTE Strings_Equal

 

[drbitboy]

COGNEX:I.ResultData[0] = 1
COGNEX:I.ResultData[1] = 0
COGNEX:I.ResultData[2] = 2
COGNEX:I.ResultData[3] = 5

Cognex Camera Results are sent to the PLC as ASCII values. 4 compares of the .DATA[n] in series to an OTE will show if all are true.

EQU COGNEX:I.ResultData[0] Print.ST16[30].DATA[0] EQU COGNEX:I.ResultData[1] Print.ST16[30].DATA[1] EQU COGNEX:I.ResultData[2] Print.ST16[31].DATA[0] EQU COGNEX:I.ResultData[3] Print.ST16[31].DATA[1] OTE Strings_Equal

+1!


So you mean, not what you wrote above, but actually this:

COGNEX:I.ResultData[0] = '1'
COGNEX:I.ResultData[1] = '0'
COGNEX:I.ResultData[2] = '2'
COGNEX:I.ResultData[3] = '5'
​

That was not at all clear in the OP, which is why I posted my caveats and assumptions.

 

[cwal61]

yes, that's correct. I just did copy/paste from his post. All Cognex camera's write ascii values to the Camera:I.ResultsData tags.

 

[plvlce]

yes, that's correct. I just did copy/paste from his post. All Cognex camera's write ascii values to the Camera:I.ResultsData tags.

This is certainly not true for *all* Cognex cameras (eg Insight 2000), but looking at the DataMan® Industrial Protocol Manual suggests it holds true for all their barcode scanners (ie all relevant to this thread).

If that's the case it does indeed drastically simplify things as you note, but OPs original post certainly seemed to suggest otherwise. We work with what we are told.

 

[drbitboy]

is the .DATA array of a string 1- or 0-based?

Edit: it's 0-based (cf. here), at least in ST

 

[MikeyN]

It is 0 based. OP could COPy their strings to second tags to get the results they are looking for. Something like

COP COGNEX:I.ResultsData[0] MonthString.DATA[0] 2

and

COP COGNEX:I.ResultsData[2] DateString.DATA[0] 2

would give them the strings 10 and 25 to compare against if that was the route they decided to take.

 

[drbitboy]

for that matter they could COPy or CONCAT both sources to 4-character strings:

COP COGNEX:I.ResultsData[0] BarcodeYYMM.DATA[0] 4

MOV 4 BarcodeYYMM.LEN

CONCAT Print.ST16[30] Print.ST16[30] TodayYYMM

EQU BarcodeYYMM TodayYYMM OTE Strings_Equal

​

Which could again all be on one line, but I think @cwal51's solution is the best.

 

[Sean Teague]

COGNEX:I.ResultData[0] = 1
COGNEX:I.ResultData[1] = 0
COGNEX:I.ResultData[2] = 2
COGNEX:I.ResultData[3] = 5

Cognex Camera Results are sent to the PLC as ASCII values. 4 compares of the .DATA[n] in series to an OTE will show if all are true.

EQU COGNEX:I.ResultData[0] Print.ST16[30].DATA[0] EQU COGNEX:I.ResultData[1] Print.ST16[30].DATA[1] EQU COGNEX:I.ResultData[2] Print.ST16[31].DATA[0] EQU COGNEX:I.ResultData[3] Print.ST16[31].DATA[1] OTE Strings_Equal

This is the simplest explanation of what i was needing and it works perfectly.

Thanks everyone for your input!

 

[cwal61]

This is certainly not true for *all* Cognex cameras (eg Insight 2000), but looking at the DataMan® Industrial Protocol Manual suggests it holds true for all their barcode scanners (ie all relevant to this thread).

If that's the case it does indeed drastically simplify things as you note, but OPs original post certainly seemed to suggest otherwise. We work with what we are told.

Plvice, Your correct. Bad wording on my part. I should have stated:

Cognex camera's will write ascii values to the Camera:I.ResultsData tags when set to SINT.

To be truthful I had to check one of my programs to verify because of the wording and responses. It was kind of like I don't remember having to do that.

 

[plvlce]

Plvice, Your correct. Bad wording on my part. I should have stated:

Cognex camera's will write ascii values to the Camera:I.ResultsData tags when set to SINT.

Fair enough. I've never used a Cognex in a situation where transferring ASCII data (or a anything else in a SINT format) would actually be beneficial, so it's not a possibility I would have though of. I don't deal with barcodes.

 

[arpus4KM]

I recently set up a Cognex barcode reader to take in a barcode, and compare it to a number set up in the system for use in sorting packages.

I'm not sure where you are having a problem? I didn't have to concatenante anything.

say I brought my data in from the cognex, and the string array the data goes into is already good as it is.

don't pull from asciistring.DATA[0], asciistring.DATA[1], asciistring.DATA[2]

just use a CPS instruction

CPS
(Source) - asciistring
(Dest) - String_To_Compare


it's already concatenated.