6534 DIO double buffered burst Ouput data incorrect

[tichung]

"using 6534 PCI DIO Card
I am generating 16 bit digital out
- with the card and double buffered Digital out
at 50Khz ~ 200Khz(external clock)
with my test data (repeat data 0x00 -> 0xff)
with request alway high

When I turn on generation (with my VC++ program)
- at firtst data is correct (repetetion of 00 to ff)
but after about 10 min . generating pattern go to "00 01 02 04 04 ... 0a 0b 0d 0d 0e 0f ... "
(some skip and repeat next data)
I don't know weather my card have problem or not
*** with my DIO32HS card and same s/w program
Data generated correctly contiunously during sevral
hours.


Send any helpful information to me.
thank you"

[John N]

Hello,

Here is a link with a small discussion of burst mode operation:
http://zone.ni.com/devzone/conceptd.nsf/2d17d611efb58b22862567a9006ffe76/d7f89691bce7de1e86256ad4007a66aa?OpenDocument

The main idea is that it is necessary to monitor the ACK and REQ lines. Both need to be high for data to be valid. Thus even though you tie your input line to high (is this really valid for your device? Is it always ready to transfer data?), the board can still choose to drop its line to indicate that new data is not yet available. As soon as both go high, the data is valid again.

It sounds like you are reading data even when the board line has been dropped. Then the data stays the same until the board is ready to transfer again. Please monitor that line so that you can d
etermine when to read and when not to read data.

Hope that helps,
John Nieri
Applications Engineer
National Instruments

[tichung]

Thank you for your comment
but, In my case ack not go to down (req fix to high
and ack doesn't go down before genration stop)

the error pattern is explained with example below
(I checked low 8bit with Logic analyzer)
expected : 17 18 19 1a 1b 1c 1d 1e 1f 20 .. 2b 2c 2d 2e 2f
current result : 17 18 19 1a 1b 1e 1f 1e 1f 20..2b 2e 2f 2e 2f
..............................
next 2 sampels of data come out in position of previous
samples and repeated. (not previous data repeatetion)
********** with my DIO 32 HS card It works correctly !!
*** Dose My 6534 card have hard ware problem???
I am using external clock and burst mode with buffer
size (65536 * x) --- I tried with various x

If you have any helpful infomation send me please.
thank you.


- tichung

[John N]

Tichung,

I was able to dig around and find something about this. I am not sure about the data going backward as yours seemed to do, but we did find a driver issue that caused the onboard memory to "stick" to the data at the end of a maximum size buffer.

Give the new driver a try. We have fixed that issue and it may be the source of the behavior you have.

http://www.ni.com/downloads.

6.9.2 is the latest as of this posting.

Thanks for your patience in me getting back to you,

John N
Applications Engineer
National Instruments