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synchronized data acquisition from DAQ terminal and GPIB port


Hello everyone,

I’m a beginner using Labview. I’m going to measure two parameter simultaneously, displacement and voltage. Displacement is captured by a laser displacement sensor (Keyence LK-031) connecting to the analog DAQ terminal, BNC 2120. The voltage is measured by a Keythley 2400 source meter which is directly connected to the PC through the GPIB port by a 183285B-02 cable. In order to inspect the phase difference between these two parameters I need two synchronize the data acquisition from DAQ terminal and GPIB port. I’m wondering if it is possible to do so. I would be more than happy if somebody can give me an example VI code of synchronizing DAQ port and GPIB port.

For better understanding of connections please check the attached photo.

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How are you acquiring the data from the GPIB instrument? Is it based on a trigger? With GPIB/Serial instruments, there is going to be some delay between sending the command to the device, it acquiring the data, converting it and sending it back to the computer.


The only way you can synchronise the measurements accurately is if you can use an external trigger connected to both the DAQ device and the source meter. The trigger will cause both instruments to start acquiring data at the same time and you can then align them in your software.


Most of the NI DAQ devices support triggering (look in the DAQmx examples in LabVIEW) - you'd need to look at the manual/options for the Keithley to see if you can use a trigger with it.

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