HOW TO CLEAR BUFFER in 1769-L36ERMS PLC

Join Date
Jan 2024
Location
India
Posts
33
Hi All,
can anyone help me with clearing data from the input that has given by the Scanner. (Clear Buffer)
I tried COP and MOV instruction to move Zero into it.
But the data is Input type so it gets flooded with data coming from the scanner again as soon as I turn my MOV intsruction off.
I cannot use serial port instruction as I get error saying 'These Instruction not allowed in this controller'
1718359328632.png
 
1. The PLC I am Using is an 1769-L36ERMS
2. I am using an 1734-232ASC Module communicating through RS-232 which is connected to my 1734-AENTR backplane.
3. The Scanner is DataLogic GBT4500.
The problem I am facing is I am getting the exact data the scanner is Scanning (In hex format which I have to convert it into String)
But when I scan for the Second time I am getting the First Data values + the second data values. (Reason I did not clear the first scan data which is clear buffer)
Now the problem is in this PLC I cannot using ACL (which is clear Buffer) instruction as the PLC doesn't support these instruction.
THEN HOW DO I CLEAR MY DATA OF PREVIOUS SCAN SO I GET IT READY FOR SECOND SCAN.
 
1. The PLC I am Using is an 1769-L36ERMS
2. I am using an 1734-232ASC Module communicating through RS-232 which is connected to my 1734-AENTR backplane.
3. The Scanner is DataLogic GBT4500.
The problem I am facing is I am getting the exact data the scanner is Scanning (In hex format which I have to convert it into String)
But when I scan for the Second time I am getting the First Data values + the second data values. (Reason I did not clear the first scan data which is clear buffer)
Now the problem is in this PLC I cannot using ACL (which is clear Buffer) instruction as the PLC doesn't support these instruction.
THEN HOW DO I CLEAR MY DATA OF PREVIOUS SCAN SO I GET IT READY FOR SECOND SCAN.
1718371049031.png
1718371075520.png
 

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This is from the 1734-232ASC user manual. Did you set up the buffer length? I would also take a look through this user manual and make sure you've configured the module correctly to work with the type and length of data you're receiving from the scanner.

1718371592380.png
 
Sounds like a scanner problem. Why is it retransmitting the previous data appended to the current data? Is there any delimiter like a <CR> character separating the two strings? Does a new string always occupy a fixed number of bytes/characters?
 
Have you got any other signals you can send to the scanner.

From what you posted it looks like the scanner is trying to send the message before the ASC card is fully initialised.

Looks like you need a bit that sends a signal to the scanner to start the communication.

Cheers

Mark
 
I have set it to 127 that is the maximum @voos.charley and have set the receive to String also tried with Array but no luck.
Also is the website server down?? takes ages to load any page
 

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I get Data from the Scanner, but it data get stacked on the top of the previous data when a new scan occurs. So i was thinking if I scan get the data and clear the buffer and again scan.
Have you got any other signals you can send to the scanner.

From what you posted it looks like the scanner is trying to send the message before the ASC card is fully initialised.

Looks like you need a bit that sends a signal to the scanner to start the communication.

Cheers

Mark
 
If you set it up with a terminating delimiter, you can use logic to obtain the string between the last instance and the previous instance. That will always be the latest data.
 
Sorry for the delayed reply. If your buffer length is set to maximum, then it may add each scan to the previous scan until it fills the buffer. Assuming you're scanning something of constant length, try setting the buffer length to the exact length you are expecting to scan and see if that works better.

The alternative of using a terminating delimiter is a good option too if changing the buffer length doesn't work or if you have to scan barcodes of different lengths.
 
I kept it to 20 once and tried and i faced same issue.. As I don't know if the value on every scan will be same range or different so I changed it back to 50 characters.
I haven't got a chance to work on the machine but once the main sequence is done I will be back on barcode scanner. Then i will post picture of the data i am getting.


Also @Ken Roach I don't know when I am logged in to this website the pages load very slow. and when I am logged out the website works normal.. Any solution??
 

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