gpib

[RTSLVU]

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@ichigo55 wrote:

I just figured it out. It had something to do with the order the cables where plugged in. Thanks for the help

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The order the cables were plugged in? 

That should have nothing to do with it, sounds like you have a bad cable or connector in there somewhere.

In my experience with GPIB and having multiple instruments (some of our test stations have 10 instruments on GPIB) the connectors are prone to intermittent contact when you start stacking them. You have to make sure the stack is firmly seated and the screws go in far enough to keep the stack of connectors from moving. After many headaches chasing down intermittent communication issues I try to not have any more than two cables on any one instrument. We have even started using GIPB distribution panels so we can have only one cable per instrument and no stacking.

I know GPIB cable are expencive, specially from NI, but L-Com has them for about 1/4 of NI prices http://search.l-com.com/search?keywords=gpib+cable

Also your USB-GPIB interface is NOT a GPIB cable, it is a USB-GPIB interface.

[crossrulz]

I agree that the order of connection should have nothing to do with anything.  This points to a bad connection somewhere.

GPIB cables should be daisy chained (A to B, B to C, C to D, etc).  But you also need to watch your cable lengths.

[billko]

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@crossrulz wrote:

I agree that the order of connection should have nothing to do with anything.  This points to a bad connection somewhere.

GPIB cables should be daisy chained (A to B, B to C, C to D, etc).  But you also need to watch your cable lengths.

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Theoertically, yes.  But I've seen some equipment that must be maybe on the very edge of spec that, even if the combined cable lengths were well short of the max length, it would start to get flaky.  On the other hand, I've seen combinations that just shouldn't work and yet they do.  (These scare me bacause if something degrades, it becomes intermittent and hard to t-shoot.)

[RTSLVU]

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@billko wrote:

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@crossrulz wrote:

I agree that the order of connection should have nothing to do with anything.  This points to a bad connection somewhere.

GPIB cables should be daisy chained (A to B, B to C, C to D, etc).  But you also need to watch your cable lengths.

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Theoertically, yes.  But I've seen some equipment that must be maybe on the very edge of spec that, even if the combined cable lengths were well short of the max length, it would start to get flaky.  On the other hand, I've seen combinations that just shouldn't work and yet they do.  (These scare me bacause if something degrades, it becomes intermittent and hard to t-shoot.)

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Indeed I have found a star topology using a GPIB distribution panel far more reliable over daisy chain.

[Dennis_Knutson]

I love the L-com cables. Especially the normal/reverse options. They allow daisy chaining without twisting the cables.