Triggering PXI SMU from External Instrument and Vice-Versa

[wcon0]

Hello,

I want to trigger PXI SMU's from an instrument outside of the PXI chassis and also use PXI SMU's to trigger an external instrument.  How is this done?

Can you point me to references about PXI triggers (papers, posts, videos, or example code)?

BR,

[santo_13]

Here you go,

https://www.ni.com/en/shop/pxi/introduction-to-the-pxi-architecture.html

https://www.ni.com/en/support/documentation/supplemental/18/using-pxi-timing-and-triggering-function...

None of the NI DCPower instruments have a front terminal to export/import triggers, hence you've to rely on other instrument's front panel terminals to route the trigger through the PXI backplane into the SMU or embedded controller's connector or the PXI Chassis' trigger connector.

[wcon0]

Wow--Thanks, Santosh!

[wcon0]

I see that we can get the trigger out of the PXI chassis if the chassis has a Timing and Synchronization Upgrade.  Is that the way?  It would be on an HDMI cable, and we would have to adapt to BNC somehow to trigger our external instrument.

Defining Trigger Signal Routes Between PXI Express Chassis With Timing and Synchronization Upgrade -...

[santo_13]

That is the way if you don't have any of the following,

1. Embedded PXI Controller with an SMB port - https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019VUOSA2&l=en-US
2. PXI Timing and synchronization modules such as 6674T
3. Another PXI instrument in the chassis with a PFI terminal (or a signal part of the connectors) on the front panel

NI has an accessory to breakout the HDMI into several BNC trigger connectors.

If you share all information about your setup, I can provide the possibilities to route trigger in/out for the SMU or other instruments.

[wcon0]

Thanks, Santhosh,

My chassis has a PXIe-8880 controller, 6570, 4141, and 4139.  (We also use 4145 and 4162.)  The external instrument is some kind of laser; I don't know the details yet.

Our program is in Python an uses nimi-python libraries.

So the controller does have an SMB connector for trigger.  I would like to use it to input a trigger from the external instrument.  Nimi-Python lets me tell an SMU channel to wait for TRIG_SMB -- at least, it doesn't make an error.

But when I measure the SMB, it is outputting 4 or 5 volts.  That doesn't seem like a trigger input to me.  How do I tell it to be an input?

BTW, what are the default voltage levels for the trigger?

[santo_13 · Accepted solution]

Typically the SMB connector would be pulled high and hence you are seeing the 5V.

To use the SMB connector, specify the trigger source in any of the NI instrument driver trigger API to the format of "/<hostname>/TRIG_SMB"

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019VUOSA2&l=en-US

As per this document, the signals on the SMB connector are LV TTL.

[wcon0]

Thanks Santhosh -- it works!

BTW, the SMB output seems to be pulled up as you said, about 1 kohm to 5 V.