Re: [hylafax-users] MPS Response problems (follow up)

[Lee Howard <faxguy@howardsilvan.com>]

On 2002.09.06 12:27 Jesse D. Sightler wrote:

> Just curious, but could someone explain what the likely causes of this
> problem are?  I know that with me it seems like the problem often goes
> away completely if I try the number again after a few hour wait.

Some time ago I wrote a rather long explanation of the "no response to 
MPS or EOP" error.  So, you may want to try to dig it up out of the 
archives.

Basically, it comes down to this: we sent a bunch of image data, sent 
the "end image" signal (RTC), and then we ask the remote directly 
following that if they got it and can view it okay in the form of "MPS" 
(meaning More Pages to Send) or "EOP" (End Of Procedure - no more 
pages).  We generally expect back either "MCF" (Message ConFirmation) 
or "RTN" (ReTraNsmit).

In the case of "no response to MPS or EOP" it means that we haven't 
heard from the remote since at least before we began sending image data 
- so a whole slew of things could have gone wrong.  Most commonly the 
problem is that the interactive timing became flawed during the 
requisite pauses either just before or just after the image data is 
sent (paper feeding, paper cutting, error correction, etc. can cause 
lags for the remote).  Sometimes the way we pause makes a difference, 
too, for example just stopping our activity or actually listening to 
the line for a period of silence (+FRS, +FTS).  If it's not timing, 
then it's probably something to do with flow-control during data 
transmission, corrupted image data, faulty firmware, etc.  This can 
also happen if the remote runs out of paper, the phone line becomes 
disconnected, etc.

Anyway, troubleshooting "no response to MPS or EOP" errors can be 
exhausting, as you can see.  It's probably one of the most common 
problems that you'll see (both in Class 1 or Class 2) if your 
configuration is otherwise working soundly, and in many cases it's not 
easily reproducible.

Generally speaking if you're running Class 2 and you see this problem 
consistenly reoccur, the only thing you can do is switch to Class 1 and 
hope for a firmware fix from the manufacturer if running in Class 2 
gives you some particular benefit or enhancement.

Lee.

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