john@wa3wbu.UUCP (John Gayman) (08/12/90)
I'm having some diffculty which I beleive someone on the Net can probably shed some light on. I'm trying to communicate with a bar-code machine on a serial port. The configuraation is very simply. I have a SVr2 machine hooked to the bar-code device at 9600 baud running through a pair of short haul modems. Distance is about 1000 feet. At the moment I'm using "dd" to collect data from the barcode unit like "dd if=/dev/ttyXX of=data". This works ok. Also I send data to the remote site to be printed by simply "catting" a data file and redirecting it to the appropriate serial port. The files I'm sending back and forth are relatively small, text files. The problem is that these files are going to get bigger. By simply sending data streams I am extremely subseptable to noise and data corruption. The barcode unit support Xmodem transfer. I cannot think of anyway in my transfer shell script to implement a xmodem transfer remotely without having a logged-in station request it. The xmodem programs I've been playing with seen to work for a PC being logged in as a terminal, they kick off something like "xmodem -sb filename", hit the PC programs download key and away it goes. Is there anyway to tell it basically "start Xmodem transfer of fileA out port tty00" and away it goes ? Assuming this procedure is more trouble than its worth, maybe there is another avenue. Would replacing my short-haul modems with a pair of MNP-type modems (dedicated line) allow me to continue using my simple "dd" and "cat" transfer method yet make it error correcting ? I have no experience with MNP modems but the way I understand it they provide an error-free (so to speak) link between a terminal and a host. Do you think they would better serve my needs. I hope I've done an adaquate job explaining my situation so that someone can offer suggestions. If I've left something out, please drop me a note and I'll try and fill you in. Thanks much! John -- John Gayman, WA3WBU | UUCP: uunet!wa3wbu!john 1869 Valley Rd. | Marysville, PA 17053 | Packet: WA3WBU @ WB3EAH