Re: [hylafax-users] T.4 capability

[Lee Howard <faxguy@xxxxxxxxxxxxxxxx>]

Jean-Pierre Radley wrote:

> Jan 10 11:12:47.47: [27829]: <-- [16:ATDT17188152525\r]
> Jan 10 11:13:16.34: [27829]: --> [7:CONNECT]
> Jan 10 11:13:47.55: [27829]: MODEM <Timeout>
>  

Ouch. A 30-second delay. That'll mess stuff up. If we believe the modem 
here it's telling us that the receiver started sending V.21 HDLC data 
sync flags but never actually sent any data for 30 seconds.

> Jan 10 11:13:47.56: [27829]: DELAY 200 ms
> Jan 10 11:13:47.77: [27829]: <-- [9:AT+FRH=3\r]
> Jan 10 11:13:47.79: [27829]: --> [7:CONNECT]
> Jan 10 11:13:47.80: [27829]: --> [2:OK]
> Jan 10 11:13:47.80: [27829]: HDLC frame too short (0 bytes)
>  

So we tried again here and got nothing.

> Jan 10 11:13:47.80: [27829]: <-- [9:AT+FRS=7\r]
> Jan 10 11:13:48.37: [27829]: --> [2:OK]
> Jan 10 11:13:48.37: [27829]: <-- [9:AT+FTH=3\r]
> Jan 10 11:13:48.42: [27829]: --> [2:CO]
>  

This "CO" to me looks like modem malfunction. So I question the accuracy 
of the modem's claims above.

> Jan 10 11:13:48.42: [27829]: DELAY 200 ms
> Jan 10 11:13:48.63: [27829]: <-- [9:AT+FRH=3\r]
> Jan 10 11:13:49.90: [27829]: --> [2:OK]
>  

This OK actually means that the AT+FRH=3 wasn't understood, and was 
interpreted as a cancellation of the previous AT+FTH=3 command. It's a 
trip-up that I believe is fixed in recent HylaFAX+ releases. But it 
probably wouldn't have helped, anyway... and the previous versions 
worked tolerably well in the same conditions... because it just repeats...

> Jan 10 11:13:49.90: [27829]: DELAY 200 ms
> Jan 10 11:13:50.11: [27829]: <-- [9:AT+FRH=3\r]
> Jan 10 11:13:52.91: [27829]: --> [16:CONÿVUŒ?€
>A]
>  

Again, the corrupted data from the modem makes me believe that the 
modem's in a faulty state.

> Jan 10 11:13:52.91: [27829]: DELAY 200 ms
> Jan 10 11:13:53.12: [27829]: <-- [9:AT+FRH=3\r]
> Jan 10 11:13:53.14: [27829]: --> [7:CONNECT]
> Jan 10 11:13:53.23: [27829]: --> [2:OK]
> Jan 10 11:13:53.23: [27829]: Remote has no T.4 receiver capability
>  

Another corrupt frame, probably. And it throws the T.4 error message 
there simply because that's the first do-or-die check made at that 
point. It's a misleading error message, but the modem doesn't seem to be 
working right in this session - so all bets are off that it's even 
checking the CRC/FCS bytes on the HDLC frame data.

Anyway --- this is just FYI in case you see the modem act up again.

Thanks,

Lee.

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