QR code scanner

[Gossamer1969]

Ok started a new job a while back and I've been handed a bunch of leftover jobs from my predecessor.

Anyhow what I have going on is a Click PLC C0-11DRE-D paired to a Cognex DMR-280Q camera and an 7" HMI

The way this system is supposed to work is the operator adds in a lot number to the PLC, the PLC tells the camera to take a picture reading the QR and reporting back the same number.

While I can see the code actively translating in the camera software the number is not being reported back to the PLC. I just get 0's/$$.

I've set the camera to work with Modbus to match the click protocol but it still isn't sending a code back.

I'm good with ladder logic, lots of years but cameras are a major weak spot for me. Hoping for some guidance since I'm a bit lost at this moment.

 

[Steve Bailey]

From your description I'm assuming the Click is the Modbus master. To me, the sequence of events should be:

1. Click sets a bit in the Cognex command word to tell Cognex to scan the QR code.
2. Click monitors the Cognex status word until it detects Cognex has acquired the QR code.
3. Click clears the bit in the Cognex command word that told Cognex to scan the QR code.
4. Click requests QR code data from the Cognex.
5. Click receives QR code data from the Cognex.

Does that cover it? Are any of the steps happening correctly?

 

[chud]

Also remember that most barcode scanners (cameras) will send the barcode or qr code data back in ascii. So dont expect to read values in decimal. Get the manual for the camera and see what modbus registers hold the values of the last code read.
Then read those registers from the plc.
Usually each character (letter / number) will be in its own byte so you will have to read multiple registers at once to get the full code depending on how long the code is

 

[Jeev]

You probably want this link: https://support.cognex.com/docs/dms...Manual/Content/Topics/PDF/DMCAP/ModbusTCP.htm