Questiion on GPIB Triggering

[SHS]

Is there a GPIB command for the HP 34401A DMM that that will cause all the
meters on the bus to trigger at the same time, assuming they are in the Wait
for Trigger state and are programmed to trigger from the bus, from that one
command?

The EXT TRIG requires some additional hardware.

What I'd like to do is insure that four meters integrate over the same time
period +/- 100uS or so. Sending serial *TRG commands spaces the start of the
integration by 25mS to 50mS so that by the time the fourth meter starts
integrating the first has already finished. Can *GET be used? Where to send
it?

Thanks,
-Bill

[DiegoF]

Hi,

The *TRG and get command work similary. The devices are addressed and then the command is send. The NI-488.2 API has the function TriggerList to simultaneously trigger several devices on the bus.

Using the get command you'll need to use the low level ibcmd function to address all the devices you want to trigger and then send the get command using ibcmd.

The Message Exchange Protocol for IEEE 488.2 defines a state called Trigger Control that is accessed when the get command is received, skiping the input queue. This is an optional feature to allow instruments to execute the trigger inmediatly. You can check with Agilent on the delay between receiving the get command and executing it.

The main limitation of simultaneous triggering in the GPIB bus
is the propagation delay and the firmware processing.

For higher levels of synchronization you can use PXI-based instrument ;).

PXI Specification Tutorial

DiegoF
National Instruments