ZModem Download

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   We are having issues with performing a "zmodem download" this time. We are downloading from a HP/UX 11 mainframe running Universe 9. We are not using any of the Multi-Value programs to perform this as they are not installed. 

1) A user will run a report from Universe

2) when the report is finished building it will

   initiate zmodem and download the report.

3) After the download is complete the user is returned

   to the previous menu and zmodem kicks out a random  

   string of characters just like this **B0800000000022d

This random string of characters then bounces the user into another menu item they cannot get out of.

Our previous terminal emulator Symantec Procomm Plus did not perform this way, is this a natural behavior for Accuterm?? any help is greatly appreciated

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jmurray Members Profile Find Members Posts Newbie Joined: January 29 2013 Location: United States Status: Offline Points: 3	Post Options Post Reply Quote jmurray Report Post Thanks(0) Quote Reply Topic: ZModem Download Posted: February 11 2014 at 7:53am
	We are having issues with performing a "zmodem download" this time. We are downloading from a HP/UX 11 mainframe running Universe 9. We are not using any of the Multi-Value programs to perform this as they are not installed. 1) A user will run a report from Universe 2) when the report is finished building it will initiate zmodem and download the report. 3) After the download is complete the user is returned to the previous menu and zmodem kicks out a random string of characters just like this **B0800000000022d This random string of characters then bounces the user into another menu item they cannot get out of. Our previous terminal emulator Symantec Procomm Plus did not perform this way, is this a natural behavior for Accuterm?? any help is greatly appreciated

PSchellenbach Members Profile Find Members Posts Admin Group Moderator Joined: December 15 2003 Location: United States Status: Offline Points: 2150	Post Options Post Reply Quote PSchellenbach Report Post Thanks(0) Quote Reply Posted: February 18 2014 at 7:20am
	Hi Joseph - Last week someone reported a similar Zmodem problem (from D3 instead of Universe), which got me wondering why zmodem is not behaving correctly. So I went searching for the culprit today, and discovered the problem is caused by a bug in the sz command on Linux/Unix. I actually dug out my original zmodem spec from 1987 to see how it is supposed to shut down, and the way it works is that when the sender (sz) is finished, before terminating, sends the two letters 'OO' (over-and-out). The receiver (AccuTerm) has received the final packet and is expecting the 'OO' to terminate the function. But somehow, perhaps as part of terminating the sz command process in Linux, the final 'OO' never gets flushed. Based on what I see in AccuTerm's debugging logs is that the sending process sends a telnet "data mark" command after sz exits, and I suspect this wipes the 'OO' from the telnet data stream. When the receiver (AccuTerm) does not get the 'OO' within a reasonable time, it re-transmits its final packet, and repeats this 3 times before giving up. This is the extra junk you are seeing after the zmodem transfer finishes. I was able to confirm this by adding a sleep(1) statement in the sz source code for zmodem, and rebuilding Linux zmodem from source. Adding the sleep(1) to the 'saybibi' function in sz.c allows these final characters to be received by AccuTerm and everything works fine. I think it unreasonable to have customers rebuild Linux zmodem from source, so I tried using the echo command to send the missing 'OO' after the sz command and that seems to get things working smoothly again. Here's the command line I tested: CMD='sh sz /home/peter/files/test3.htm; echo OO' EXECUTE CMD Hope this explains what is happening and helps work around the problem. Thanks, Pete