instrument front panel gets locked out

[sekhar]

I am using a HP6626A power supply and a HP34401A DMM in a test application.
The instruments behaves fine when operating from the remote GPIB interface, but when the test is finished the instrument front panels are locked out.
The instruments do not even respond to the "Local" button on the front panel. The only way i can use the front panel again is to cycle the power on the instruments.
It seems that the GPIB "Local Lockout" (LCL) command is being issued somewhere, but I know that i am not sending this command.
Could someone give me any ideas on how to debug this problem.

Thanks in advance,
Sekhar

[GPIB_Guru]

If you wish to determine when the LLO command is going across the bus, you can run NI-Spy to capture all calls that are being made by the application.

To check to see if the device in in the RWLS (Remote with Lockout State), you can simply remove the GPIB cable. If the device now responds to front panel operations, you were likely in RWLS state.

The reason why removing the cable works is that a device automatically transitions to the LOCS (Local) state when the REN line is unasserted. To programmatically deassert the Remote Enable (REN) line on the GPIB bus. There are options in NI-488.2 (ibsre) and in VISA (viGpibControlRen) to perform this deassertion. If your application is not changeable, you can launch ibic and make the following calls:
ibfind gpib0

ibsre 0
ibonl 0

Good luck.