> has someone running a HP Scanjet IIp (or another HP scanner) on Irix 6.2
> ?
> There is a problem with such a combination that the scanner is
> recognized
> during the SCSI INQUIRE command (vendor, model and firmware is read
> back),
> but the scanner does not give any response to other commands.
> The TEST UNIT READY seems also to work.
> Has someone encountered a similar problem on Irix and how was it solved
> ?
Hi, Peter. I don't know if this is related, but I had trouble with partial
SCL responses when I was developing my experimental support for HP OfficeJets
connected to HP JetDirect print servers (see http://www.ns.net/~paschal/sane).
There were situations where the device apparently split up the SCL response
into different packets, which caused read() on the client to return only the
first part. This caused a great deal of confusion with the upper levels of
the HP SCL backend, due to both the short initial response, and the remainder
of the response, which was interpreted as a malformed response to a subsequent
request. I solved these problems by adding a select-and-read loop to my I/O
code, with support for different timeouts for the first and subsequent
select()s. See hp_jdex_read() and hp_jdex_select() in hp-jdex.c.
Perhaps the ScanJetIIp/Irix6.2 problem is caused by a similar sensitivity
in the HP backend to unusual timeout behaviour in the underlying OS, although
it's strange that read() would return immediately with no data. I wonder if
the fd is somehow defaulting to non-blocking mode? Just speculating aloud
here...
David
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