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Currently using 8 6551 in parallel what can I do to increase operations

We noticed as we add a 6551 our test time increases.  It's very noticeable when your using 8. 

Most patterns are unique and calculated on the fly not knowing the result. Currently were using code compare to read data back by setting compare to all lows to minimize data.

The cards are Setup once and the handles kept open clearing the buffer if different pattern is used, else we just use initiate.


Is there anything else we can do to help with test time.

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Hi Frankmesa,


Could you give me a little more information about your system?  What chassis are you using?  To what slots are you adding the 6551s?


Sara Lewandroski
Applications Engineer | National Instruments
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We found that the Bus bandwidth couldnt handle the volumn of data both to card and from card. So we stored what patterns we could on the card. As for the data coming back we used hardware compare. We built a vector chart of each data segment and set hardware compare to 0's. Once an error occured we take the vector error and put a 1 in the correct location in the chart reconstructing our data with only half the data coming back. This greatly reduced our bandwidth. Combining these two things we were able to cut our time more than half. This works well for us since these are not scan patterns this is reading the output of the part.

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