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| Author | Topic |
| rgarabedian Tl Posts: 5 USA | Posted - 1/14/2003 8:21:04 AM    Hi, I'm seeing a problem that is driving me absolutely batty. I have some software that auto dials a bunch of different systems. The app runs on Linux, uses C-Kermit and an external 3Com V.Everything Modem. Everything works great, until the other day when I tried connecting to some new systems. When I try with the software, all it sees is garbage characters. However, when I try with my laptop using Windows Hypertermail and/or Tera Term (Toshiba Software Modem AMR) I can connect and login to these systems. The only difference I can see between the two are the connect strings. With the laptop, the connect string looks like: CONNECT 2400 MNP5 With the software (and courier modem), it looks like this: CONNECT 2400 ARQ So my wild guess here is that something is wrong with how the courier modem is negotiating the compression type. So I'm trying to force the courier into MNP5 compression with something like: &K1S27.5=1 But that doesn't seem to work as the connect string still shows: CONNECT 2400 ARQ I'm pretty lost with this. Anyone have ideas? Am I completely off base? Any thoughts are greatly appreciated. |
| charles Tl Posts: 5879 USA | Posted - 1/14/2003 9:42:22 AM CONNECT 2400/ARQ ARQ means error Correction CONNECT 2400/ARQ/LAP-M LAP-M is data compression, ARQ is error correction. CONNNECT2400/MNP Connection using MNP protocols
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| rgarabedian Tl Posts: 5 USA | Posted - 1/14/2003 9:59:55 AM Okay, so I'm misunderstanding the ARQ and MNP5 on the CONNECT line. Thanks for the hints. I just tried to connect to this same system using Tera Term on a completely different computer. (Don't know what kind of modem it uses unfortunately). Was able to connect, but the connect string is different still: CONNECT 2400/ARQ/MNP/MNP5 So if I'm understanding this correctly, it appears like connecting with error correction isn't causing a problem, but not using MNP5 protocols is? Or is looking at the CONNECT result just a red herring and the wrong way to troubleshoot? Thanks for the link. I'm looking at the actual Courier modem manual. THat's where I getting my info and init strings from. Every string I've tried so far - from nothing to many - doesn't seem to change the behavior. I'm still reading garbage characters. And I can never seem to get the CONNECT message to show the connection is using MNP5 protocols. Thanks for the note. |
| charles Tl Posts: 5879 USA | Posted - 1/14/2003 10:47:30 AM Might try &A3 also go down the page I posted and look under results code display commands Q,v,x,&An |
| charles Tl Posts: 5879 USA | Posted - 1/14/2003 10:53:34 AM I see that MNP5 has to have flow control do you have it set to hardware? |
| charles Tl Posts: 5879 USA | Posted - 1/14/2003 10:55:25 AM Flow Control The mechanism that compensates for differences in the flow of data input to, and output from, a modem or other device. Flow control is also the single biggest source of modem headaches. If flow control settings are improperly configured, it may be impossible to connect to a remote system, or the transfer rate may be incredibly slow, or a download may spontaneously abort. If you are downloading a file and see high numbers of errors and re-transmits, you should check the internal modem settings against your communication program's settings - BOTH SHOULD BE SET TO THE SAME TYPE OF FLOW CONTROL. If your modem is internally configured for hardware flow control, your communications software should also be set likewise. Flow control refers to the means whereby a receiving computer can signal to a sending computer to pause and resume the transmission of data. Flow control also refers to the link between the personal computer and the modem attached to it. Hardware flow control uses separate wires in the modem cable to signal stop and start requests. Software flow control inserts special characters in the data stream being transmitted, XOFF (Control-S) and XON (Control-Q). Software flow control suffers from the following limitations: 1) you might need to actually send Control-S and Control-Q in your data stream, as when you are using the EMACS editor; 2) these software commands can become garbled in transmission and freeze your session; and, 3) you might experience timing problems where the remote modem's data buffer overflows (and you lose data) before the "stop sending" control code reaches the other end of the connection. Flow control should be enabled in both directions - that is from computer to modem, and from modem to computer. Only your modem manual can tell you how to set one or the other types of flow control. The commands differ between different modem brands |
| rgarabedian Tl Posts: 5 USA | Posted - 1/14/2003 11:27:48 AM Whoohooo! Your suggestion of flow control brought me major progress. I use C-kermit, so I specified Harware flow control with: SET FLOW-CONTROL RTS/CTS I then used an init string that forced MNP5 and hardware control with: AT&F1&K1S27.5=1 Now, when I connect I see: CONNECT 2400/ARQ/MNP/MNP5 and I'm not getting garbage anymore. Something is still screwy though because the first thing I see is an incorrect login message. It's almost as if the remote computer thinks I tried to send over login information when in fact I really didn't. The next thing I see is this string: ERROR CONTROL Not sure where that comes from, but I've never seen it before. So here is the part I'm really confused about. I've NEVER had to go through all this tomfoolery to get my system to connect with another before. Like I said earlier, I successfully interact serially with over 50 systems. In this case, do you think it's because this particular modem is configured to only use MNP protocols? Or could this modem be broken maybe? Anyway, thanks so much for your hints. At least I have something concrete to go on now.
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| charles Tl Posts: 5879 USA | Posted - 1/15/2003 1:59:04 AM Do you need a log in script to log in to this modem.May be also need to. set port set speed set error control MNP incompatibility: The modem is set to &M5 and the remote modem does not have MNP compatibility, or there was an MNP negotiation procedure error.
Edited by - charles on 1/15/03 8:14:31 AM |
| charles Tl Posts: 5879 USA | Posted - 1/15/2003 8:03:14 AM http://www.ics.mq.edu.au/docs/general/technical/modem/MT-Error.html
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| rgarabedian Tl Posts: 5 USA | Posted - 1/17/2003 6:12:50 AM Sorry it's taken me so long to update - I've been pretty busy. So the problem seems to be solved. All I needed was to change the init string from AT&F0 (Loads no flow control template) to AT&F1 (Loads Hardware flow control templage). Thanks a lot for your help! |
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