lakeshore 475 gaussmeter+TRIGGER

[francescatiziani]

Hello,

I'm using a 475 Lakeshore gaussmeter and I need to measure magnetic field by having a trigger event as start condition.

There is a hardware, TTL level, trigger into the instrument that can be used to initiate the data log sequence but the user's manual doesn't explain how to use it. In lsci475 library there aren't trigger examples too.

I connected my trigger signal input to the Auxiliary I/O connector and i i modified my acquisition program by using the *TRG command (from the user's guide: *TRG = trigger event. Starts the datalog capture mode. This command is equivalent in operation to the DLOG command).

I did it by following the DLOG library's examples, see that these two commands are equivalent and i expected that the field acquisition started only at the trigger signal. What i get is, instead, the same measure as before, when the trigger was not connected.
Have you ever used the trigger option with this gaussmeter? Are there any other commands that i have to change or modify?

Please help.

Thank you in advance,

best reguards.

[giu7]

Hello,

can I ask you if you are using LabVIEW to acquire data?

Regards.

[francescatiziani]

Hello,

yes I'm using LabVIEW.

[ned87]

Hi Francesca,

could you be more precise about what hardware configuration you're using? Is the gaussmeter the only piece of hardware present? How is your system intended to interact with NI software?

Regards

[Dennis_Knutson]

It's unclear what you are using for the source of the hardware trigger. It sounds like you are software triggering it to generate a hardware trigger and that does not make much sense.

[francescatiziani]

The DSP 457 gaussmeter is connected to the computer by serial interface and receives data from a hall probe inside a bending magnet.

I'm using LabVIEW to acquire field measurements but I want  to use a trigger input to start the aquisition in order to synchronize it with the timing of my sperimental setup.

This gaussmeter has the possibility to do it, user's manual says that "a TTL-level hardware trigger into the instrument can be used to initiate the data log sequence". I connected a manual trigger to the Auxiliary I/O connector of the gaussmeter: when I press the botton it generates the trigger input signal to start the acquisition.

I modified the acquisition program by using the *TRG command that I found in the interface command list: *TRG represents the trigger event and starts the datalog capture mode. I used it instead of the DLOG command (user's manual says they are equivalent) but it's not working: it seems that the trigger signal input is not received, so that data acquisition starts independently of it.

There aren't other commands related to trigger events and I couldn't find any example about it in the lsci475 library.

[Dennis_Knutson]

The *TRG is a software trigger. You would need to configure the device to use that instead of the hardware trigger. There is no signal to be received when you do a software trigger. If the software trigger is not working, you should probably contact the vendor to verify you have the instrument set-up correctly. It's also unclear what sort of synchronization you need. Does the experiment depend on LabVIEW to detect something and then generate the software trigger? What would be the difference between generating the software trigger or just issuing the DLOG command?

[francescatiziani]

I apologize if I can't explain properly the problem but I never done something like this before.

I would like that the gaussmeter started the field acquisition only when it recieves an external trigger signal by Auxiliary I/O connector: now i'm using a manual trigger just to try, but in the final setup it will be a timing signal coming from other instruments of the system.

I think I don't need to generate a software trigger because the trigger signal already exists, I only want that the instrument detects it and then starts the data acquisition.

I supposed *TRG was the command to tell the gaussmeter to start acquiring under the condition of having received the trigger signal, not the command to create a new software trigger.

[Dennis_Knutson]

Then forget about the *TRG command. You need to provide the signal from the other instrument. It would work the same way as your manual trigger does as long as the signal is the same.