I am using a control logix 1756-L55 and have two stationary scanners on my line, they are fed to a Black Box brand sequencer and then to the serial port.
My problem is (I think) noise that is hitting my scanner cabling or the sequencer itself. We are having to power down the black box, and power it back up to get it to clear. I have contacted them and can find no solution. There are times when this locks up the serial port on the processor. I have in place a bit to clear the port, but I need advise on how to find the source of the noise or whatever it is so I can make a "Fix".
Has anyone had simular problems? Any one have a good remedy?
Thanks
Will

Will:

Couple of observations and questions.

1. What is the distance involved from scanner to black box and black box to CLGX?

2. What is the potential noise source?

Have you considered using 1734-RS232 flex io modules and either ControlNet or EthernetIP. This would let you eliminate the black box by having multiple serial ports one 1734-RS232 per scanner. It would also allow you to determine which scanner is the noise source.