GPIB "instruments not found"

[Bob HSN]

I am trying to use a National Instruments GPIB card with a couple of HP instruments - a relatively new HP 53131A Counter/Timer and an older HP 3421A DAQ. NI Measurement & Automation Explorer 3.0.0.3014 shows "instruments not found" for both instruments. Both instruments pass internal tests for their GPIB functions and work with an alternate GPIB controler (an ancient HP-85). The NI GPIB card passes all functional tests and I have tried multiple GPIB cables.

When I run Interactive Control (IBIC) as per the instructions at www.ni.com/support/gpib/max/ibic.htm, I get the following for both instruments (with different GPIB addresses):

ibfind gpib0

gpib0: ibpad 0
[0110]
previous value 0

gpib0: ibrsc 1
[0110]
n>
previous value 1

gpib0: ibsic
[0110]

gpib0: ibln 9 0
[8110]
error ECIC
Listen: False

I have checked that both instruments are not in a talk only mode.

Note: GPIB address for 3421A is 9 and GPIB address for 53131A is 3 I have assumed that SAD for both instruments is 0.

Does anyone have any suggestions as to where the problem/solution might be?

Bob Holmström

[GPIB_Guru]

The fact the ATN is already asserted on the bus is the concern. If you have another controller on the system (is the other GPIB board still connected?) that is asserting ATN, that will prevent the NI board from being the active controller in charge. This in turn will prevent the NI board from being able to detect device on the bus.

The ATN could be asserted for a number of reasons, such as:
1) Another system controller is on the bus that is driving ATN high.
2) You have a cable problem that is shorting the ATN line.
3) Your cable is upside down (?) so the lines are misconnected. Typically this cannot happen as cables are keyed, but I have seen this before with an instrument that had the connector keying removed.
4) The GPIB board has a problem

If you
disconnect the cable from the GPIB board (the NI board) and relaunch ibic and try the first four commands again and you get the same result, I would think you have a defective board. If instead of 0110 for the status you get 0130 than the board is likely working find and you have another device on the bus asserting ATN. If so, disconnect each device from the bus until you determine which device is asserting ATN.

This should get you started.

[Bob HSN]

Thank you for your quick response.

There is no other GPIB controller currently installed - there was a different one installed several months ago but it is no longer in the computer.

I disconnected the cable and relaunched ibic. The results are the same as before i.e. all begin with [0110]. The board passes the tests that are run from the 488.2 troubleshooting wizard - are there any other tests I can run?

Thanks again

Bob Holmström

[GPIB_Guru]

If you have no cables connected to the GPIB board and you get 0110 in ibic, it sounds to me like something is wrong. You should probably contact NI Technical Support.

Sorry I don't have much additional help. If the GPIB board detects the ATN high, it is unable to transition the controller state machine to the CACS state. Therefore, it is unable to send command bytes. If there are no cables connected to the GPIB board and ATN is still being asserted, something seems wrong.