Synchronization Problem: PXI-4498 with Agilent 33120a Function Generator

[oldmajor2021]

Hello everyone,

Currently having issues getting proper synchronization between my NI PXI-4498 DAQ card and external HP / Agilent 33120A function generator. The DAQ card is set inside a NI PXI-1042Q chassis, and the Agilent has the Option 001 phase-lock assembly.

My setup consists of loading a periodic arbitrary waveform into the Agilent using a separate LabVIEW VI. The signal is a multisine generated in MATLAB to approximate random noise across different bandwidths (10-100 kHz, 5-20 kHz, etc) although I dont think the signal content matters in this case. The acquistion VI is set to sample at 204800 Hz (maximum for the card, but necessary as we are interested in acoustic signals up to 100 kHz) continously for a specified time, and then export the data as a single TDMS file. When monitoring the acquisition by looking at a single block in real time there is clear drift.

Have tried using the rear panel reference clock input/outputs in both directions (output from function generator to DAQ, and output from DAQ to function generator respectively) but neither seems to work. Both are specified as 10 MHz clocks. Fairly sure these hardware additions were intentionally designed to solve this problem, and I have had success with different variations of NI DAQ cards and Agilent generators before using this method, but sadly that equipment is unavailable. Any suggestions?

Many thanks!

[Beutlich]

Each device will require some setup to use the clocking features. You can import or export either way for either device, so you will want to pick which device is the source of the clock. Suppose you wanted to import the clock to the 4498. You will want to route to the chassis clock, which is described in the 1042Q User Manual on page 2-10. It reads "When the backplane detects a 10 MHz signal on the 10 MHz REF IN connector, it automatically overrides the 10 MHz clock provided by the backplane and uses the externally provided clock." So, plugging in the 10 MHz clock will automatically put the clock on the chassis, but then you need to setup your 4498 task to clock from the PXI back plane, which is shown well in this DSA Synchronization Example.

The Agilent device has information about how to setup the clocking features also in the Agilent 33120A Function/Arbitrary Waveform Generator on page 7 or 10 or so. Notice that it also requires some programmatic control to set the clock porting correctly. You may want to route triggers as well as clocks, and the information is in those same sources.