primax: Thread: D600 further investigations


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Subject: D600 further investigations
From: Mike Rothon ####@####.####
Date: 10 Oct 2002 21:10:40 -0000
Message-Id: <200210102212.19917.miker@mazpro.co.uk>

I have made some more detailed investigations since my last post:

The problems that I was experiencing before that I thought were down to the 
resolution are not that simple.

In the function get_scan_data (libprimax.c) the code enters a while loop 
waiting for a 16-bit value to be read from the port which matches the 
total_width -1.

Depending on what parameters are supplied to the scan, it is possible for this 
code to lock up, never reading an appropriate value from the port.

When the code locks up, there seems to be garbage being read from the port.

The factors which affect the succesful outcome of the scan are:

1. Resolution. The lower the resolution, the better.

2. Scan width. The lower the scan width, the better.

3. Scan speed. The higher the scan speed setting the better.

i.e. scanning -d5x10 -s15 -r150 works fine but -d7x10 -s0 -r600 does not.

Given that the number of bytes read in a single line are dependant on the 
width and resolution, this leads me to believe that there is a timing 
problem.

*****************************
Assistance Required!!!!!!
*****************************

I need some help from someone who is familiar with the scanner protocols who 
can tell me what the values being read during the get_scan_data routine are 
doing. It seems to me that initially there is a count that indicates how many 
bytes have been scanned into the FIFO, and then when the FIFO is full it is 
read en-block.

It looks as though that either with a lot of data (=high resolution x wide 
scan) the FIFO is overflowing and the byte count data is being corrupted.

I would like to see the documentation received from Primax regarding the 
scanners - did it include anything on the D600?


Finally, how do I use the saned daemon? Do I need to edit a config file? There 
doesn't seem to be any documentation on using the Xsane interface.

Bye,

Mike.









Subject: Re: D600 further investigations
From: Andre Herms ####@####.####
Date: 11 Oct 2002 08:52:35 -0000
Message-Id: <200210111049.28166.aherms@cs.uni-magdeburg.de>

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>
> *****************************
> Assistance Required!!!!!!
> *****************************
>
> I need some help from someone who is familiar with the scanner protocols
> who can tell me what the values being read during the get_scan_data routine
> are doing. It seems to me that initially there is a count that indicates
> how many bytes have been scanned into the FIFO, and then when the FIFO is
> full it is read en-block.
>
> It looks as though that either with a lot of data (=high resolution x wide
> scan) the FIFO is overflowing and the byte count data is being corrupted.

This was also my fist thought. As I don't own a D600 I cannot prove. But if 
this FIFO is a really a FIFO, you can take out some data while the scanner is 
still putting some on the other end. 
So it would be in general a good idea to fetch data as soon as posibble. Maybe 
the scan gets faster and we can beat the windows driver :-).

So let's try it. Maybe the scanner work with this.

One Question: does it always work with 300dpi?

Gruss,

Andre

- -- 
Andre Herms                   ####@####.####
                              http://www.cs.uni-magdeburg.de/~aherms
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Subject: Re: D600 further investigations
From: "Mike Rothon" ####@####.####
Date: 11 Oct 2002 10:26:24 -0000
Message-Id: <006e01c27110$0ae01bf0$7d01a8c0@mike>

> One Question: does it always work with 300dpi?

Yep, it always works at 300 dpi, irrespective of the speed and the scan
size.

It also pretty much works at 450 dpi. Maybe I am just fussy, but it would be
great to be able to scan full page at the max. resolution.

Finally there is some code that sets a variable "datarate" however I don't
see this variable used anywhere. This is also a command line option. Do you
know where datarate is used?

Thanks,

Mike.

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