Re: Identifying where flow control is happening

Models wrote:
> I am trying to get a better understanding of the computer to modem data
> flow in HylaFAX.
>
> In the trace logs, regardless of the DTC-DCE speed (high 115,200 and low
> 19,200), I see the following:
>
> ===============================
>
> Jan 08 01:22:29.99: [ 3595]: MODEM set XON/XOFF/FLUSH: input
> interpreted, output disabled
> Jan 08 01:22:29.99: [ 3595]: DELAY 200 ms
> Jan 08 01:22:30.18: [ 3595]: <-- [11:AT+FTM=146\r]
> Jan 08 01:22:30.43: [ 3595]: --> [7:CONNECT]
> Jan 08 01:22:30.43: [ 3595]: <-- data [1036]
> Jan 08 01:22:30.43: [ 3595]: <-- data [1034]
> Jan 08 01:22:30.43: [ 3595]: <-- data [1029]
> Jan 08 01:22:30.43: [ 3595]: <-- data [1037]
> Jan 08 01:22:30.77: [ 3595]: <-- data [1049]
> Jan 08 01:22:30.77: [ 3595]: <-- data [1045]
> Jan 08 01:22:30.77: [ 3595]: <-- data [1053]
> Jan 08 01:22:30.77: [ 3595]: <-- data [1050]
> Jan 08 01:22:31.88: [ 3595]: <-- data [1066]
> Jan 08 01:22:32.52: [ 3595]: <-- data [1061]
> Jan 08 01:22:33.15: [ 3595]: <-- data [1056]
> Jan 08 01:22:33.78: [ 3595]: <-- data [1058]
> Jan 08 01:22:33.78: [ 3595]: <-- data [1050]
> Jan 08 01:22:34.35: [ 3595]: <-- data [1050]
> Jan 08 01:22:34.92: [ 3595]: <-- data [1057]
> Jan 08 01:22:35.48: [ 3595]: <-- data [1059]
> Jan 08 01:22:36.12: [ 3595]: <-- data [1039]
> Jan 08 01:22:36.75: [ 3595]: <-- data [1041]
> Jan 08 01:22:37.38: [ 3595]: <-- data [1042]
> Jan 08 01:22:38.02: [ 3595]: <-- data [1044]
> Jan 08 01:22:38.62: [ 3595]: <-- data [1038]
> Jan 08 01:22:39.18: [ 3595]: <-- data [1040]
> Jan 08 01:22:39.75: [ 3595]: <-- data [1047]
> Jan 08 01:22:40.32: [ 3595]: <-- data [1038]
> Jan 08 01:22:40.88: [ 3595]: <-- data [1032]
> Jan 08 01:22:41.45: [ 3595]: <-- data [1040]
> Jan 08 01:22:42.02: [ 3595]: <-- data [1033]
> Jan 08 01:22:42.58: [ 3595]: <-- data [1045]
> Jan 08 01:22:43.18: [ 3595]: <-- data [1042]
> Jan 08 01:22:43.82: [ 3595]: <-- data [1038]
> Jan 08 01:22:44.45: [ 3595]: <-- data [907]
> Jan 08 01:22:45.08: [ 3595]: <-- data [2]
> Jan 08 01:22:48.02: [ 3595]: --> [2:OK]
> Jan 08 01:22:48.02: [ 3595]: MODEM set XON/XOFF/DRAIN: input ignored,
> output disabled
>
> ===============================
>
> I'm trying to understand why data transfer is taking place in blocks of
> a little over 1K, as opposed to some other value.

The way that HylaFAX prepares the data for transmission, it takes 1K of 
image data, adds DLEs as needed, and then sends it.

> Is there a
> correlation to flow control.

No.  Flow control can be noticed by the timestamps.  The flow control 
will happen in the middle of a block of data, will pause things, etc.  
So flow control can only be noticed by examining the timestamps of the 
data writes.

Thanks,

Lee.


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