Friday, August 29, 2008

MSP 455 XL & Serial port

I had to deal with this printer today at CRIS (Center for Railways Information Systems). We are doing POC (Proof Of Concept: A stage making the company eligible for taking part in CRIS tenders) for UTS (Un-reserved Ticketing System) and PRS (Passenger Reservation System) terminals at CRIS. What they want is to be able to run both applications simultaneously on the same thin client. However, both UTS and PRS need to print to line printers and the line printers of CRIS does not support USB. The solution was to use serial port for PRS and parallel port for UTS. MSP 455 has both ports and we decided to use it for testing.
However, we did not know the baud rates and the kind of cable to be used with the printer. We tried with a cross serial cable first. We tried all the bauds possible. (Baud setting: stty -F /dev/ttyS0 9600). Eventually I called up the TVS 'care line'. After a few hops, I reached a guy who told me that baud is 19200 and I need special TVS printer cables.
At this point I asked the hardware engineer with me to change the cable from cross to straight. He did that and then I started with 19200 and went all the way up to 1Mbps. Nope... only junk. Then I noticed that as I increase the speed, the data printed is getting lesser and lesser. => The speed need to be very low. I then tried 9600 and viola... It worked!
The lesson is MSP 455 from TVS needs a straight serial cable and it works at 9600 baud. We did simultaneous printing for UTS and PRS and it worked fine. Now I need to find a way to get the status of the serial printer. Will work on that tomorrow.

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