nbladt@aut.UUCP (Norbert Bladt) (03/08/91)
Hello NCR Tower users ! A few weeks ago I asked for some help with the "xsend" program. We try to use it for printing via X.25, i.e. the printer is connected to a hardware PAD. The result was and is that after it works OK once, in all the following attempts to print the last lines of the file were not printed. I used a serial line analyzer to figure out what happens. Here it goes: 1. The printer does not receive more lines than are printed. I.e. no lines are stored in the printers buffer or they are printed immediately after setting the printer off-line. 2. The PAD receives more lines than the printer. However, before the PAD gets all the lines of the file, it receives a Clear Request call and flushes the output buffer. 3. The Tower sends more lines of the file than the PAD receives. But some lines of the file are not sent by the Tower. Instead a Clear Request packet is sent and this results in flushing the buffers in the public X.25 network. It boils down to the following: The Tower doesn't send all the lines in the file to the X.25 network ! I had contact with our local support and, they are helpful to a certain degree, they suggested using "xvc" for printing. This tool seems to be better suited to our needs than "xsend". "xsend" expects some intelligence on the other side, i.e. it expects that the other site (or side :-)) to clear the connection which the printer never does, of course. So, there is a timeout (1 min.) until "xsend" forces the disconnect of the line. The manual to "xvc" (about five lines of text, not only formatted wrong but also far too short for a good explanation) seems to indicate that a X25 connection is done and a program is executed (parameter to "xvc") which has a X.25 tty as its stdin and stdout. Now, the first attempt I did was to call this interactively. I tried something like: xvc -d X06tty AnX.25address 'cat /etc/rc' The error message was: xvc: callnua failed ! (13) Couldn't open Xnntty check error code. Permission denied. I called the local support and I got the right answer: use 06 instead of X06tty ! Of course, this is not in the manual. So, I did: xvc -d 06 X.25address 'cat /etc/rc' Now, I got the following: xvc: callnua failed ! (13) Couldn't write to xacunn check error code. Permission denied. However, all permissions on these devices are set that everyone can read and write to them. I have read parts of the manual, but can't figure out why I get this error message. I asked the local support whether I must configure something, but they said NO. Of course, I didn't try this with the added complexity of "lp" and its related programs. I don't think that this will work. BWT I tried all this as a normal user and as root. If somebody can help me solving this problem, I will be glad. Our customers want to print files via X.25 (e.g., 1120 lines) and they need the whole list to show up. Thank you, Norbert Bladt. P.S. I got mail from a person in Portugal with other horror stories about "xsend" and their own implementation of it even crashing the system (spurious interrupt - System HALTED). Although it is a different hardware (we have 650, they have 500/700) and software (we: V.2, they V.3) I wouldn't like writing a better "xsend" myself considering their experiences. However, if somebody has written such a program which really works, I would like to get it. I think, we might even pay for the sources. Many thanks, again.