Hi All -
I am working to connect a barcode reader to a Vision 120 PLC via RS232. I have two barcode readers on hand - a Motorola Symbol LS4278 (which reads 1D and 2D codes), and a 1D-only Royal PS700-LSR. Both readers are set up the same way - serial cable with external power input into the scanner, connected to the PLC by a DB9 to RJ45 adapter.
When connected to a Serial-to-USB converter to the computer, both scanners send the same data to the Serial Terminal (I am using Hercules). But when connected to the PLC, the Royal scanner data is read as expected, but nothing happens when scanning codes with the Symbol scanner.
On the PLC, the Session Complete bit is never set by the Protocol Scan block so none of the other processing is triggered when the Symbol scanner is connected. With the Royal scanner, each scan flips the Session Complete bit, and data is copied and formatted correctly.
When the scanners are connected to the computer, I see the exact same hex characters in Hercules from both scanners.
PLC program attached.
I have tried and confirmed various serial communication settings (baud rate, STX/ETX chars, handshaking, etc.) to match between the scanner and the PLC, and I have worked through the suggestions in this thread:
Can anyone suggest what the difference between the two readers might be? I need to make the Symbol reader work since the system will read 2D barcodes.