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problems with 1byte data width PXI-6562

Hi,
    I was wondering if anyone has faced problems with dynamic data acquisition with a 1 byte data width on a PXI-6562. I'm trying to stream in data to the hard disk from only 2 lvds channels at the rising edge of a 25MHz external clock. My vi is just about able to do the job on my PXI-8105 (provided I don't run any applications in the background). The problem I am facing is that the captured data is all zeros - all channels are blank when I open the hws file. When I change the data width property to 2 bytes, I am able to capture my data without any issues (i am using channels betw 0-7 in all cases). However with a 1D U16 format at 25Mbps, my hard disk is not fast enough to handle the additional 1 byte and my vi terminates with a 'data overwrite error'. So I've been trying to get the 1D U8 to work with no success.
 
I am using the Continuous Acquisition- Stream to Disk.vi modified for a data width of 1 byte which I've attached with this post. I am also using niHSDIO driver ver 1.4.3.2 which is supposed to be able to handle configurable acquisition data widths, and labview v8.2. Does anyone have a solution to this problem?
 
Thank you,
Cosh
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Hi Cosh,
 
We were able to duplicate the issue of using a 1-byte acquisition data width on the PXI-6562.  This was reported to R&D (CAR ID# 45UDPVTC) for further investigation.  Currently the only workaround I can provide is to use a 2-byte data width.  Thank you for the feedback, and I will try to post back to this discussion forum if a different workaround arises. 
 
Regards,
 
Nicholas B
Applications Engineering
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Hi Nicholas,
                   Thanks for your reply. I am unable to use a 2 byte width at 25MHz because of limitations in my hard disk write speed. The rate at which data streams to hard disk doubles if I use a 2 byte width instead of 1 byte, and I am using a SATA HD. I would appreciate it if you could let me know when this issue is resolved.

Thanks,
Cosh
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Is there a resolution to this issue or a new workaround.  We are seeing the same problem using the pxi-6561.  The workaround is OK, but we would prefer to use the byte data so that we can read more data in.
 
Thanks,
Dan
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Hello,
This issue was resolved in NI-HSDIO 1.5.3:
 
As indicated in the 1.5.3 readme:
45UDPVTC Fixed an issue with NI 656x acquisition returning invalid data when data width is set to 1 byte.
 
Give this a try.
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Thank you, that took care of the problem.

Dan

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