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Message ID: 493     Entry time: 01 Jul 2008
Author: Jimmy Ngai 
Topic: Forum 
Subject: CAEN V792N QDC with MIDAS 
Dear All,

I have a problem when testing the V792N 16 CH QDC with the V1718 VME-USB 
Bridge on Scientific Linux 5.1 i386 (kernel 2.6.18-53.1.21.e15).

The problem is that the V792N does not response normally after a few minutes 
of continuous polling and readout of data. It seems like the V792N is hanged 
and a hardware reset of the VME system is required to bring it working again. 
If I do not poll for DREADY first and directly read the Output Buffer 
continuously, the system can work properly.

I have worked on this problem many days but I cannot find any clues to solve 
it. I have tried to use the CAENVMEDemo program (with some modifications) to 
do the same thing (polling and readout) and it works fine. CAEN technical 
support also doesn't know why the VME system is hanged. I think it might be a 
problem of MIDAS itself. I have tried with MIDAS revision 4132 and the trunk 
version, but the problem is still there. Is there any parameter in MIDAS 
(buffer size etc?) which may cause this problem? I have attached my frontend 
code and drivers for your reference.

Thank you for your kind attention.

Best Regards,
Jimmy
Attachment 1: frontend.c  8 kB  | Show | Show all
Attachment 2: v1718.c  7 kB  | Show | Show all
Attachment 3: v792n.h  7 kB  | Show | Show all
Attachment 4: v792n.c  20 kB  | Show | Show all
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