Is it possible to route trigger signals between two PXI-1002 chassis using PXI-8335?

[Max1744]

Hi,

as the topic says, I'm interessted in routing a trigger signal between two PXI-1002 chassis. At the moment these two chassis are connected by an MXI-3 system using PXI-8335 cards. The software is Labview 2010 sp1 and the NIScope 380 drivers.

We want to keep the digitizers (one PXI-5122 per Chassis) galvanically seperated due to the requirements of our measurement! The chassis are connected using the fiber optic cable. This explains why I can't just use the star trigger, or connect the cards via "Trigger" or "clk" (the in/outputs at the front of the cards).

I've found some examples, but they all seem to be designed for the use with one chassis only, I will later refer to the examples that inspired me until this point. Every guide explaining the synchronization of multi chassis systems seems to use other hardware or VI's not accesible to me. This makes me wonder if my hardware has the capacibilities I need.

The first picture shows roughly where I started from (sorry I can't post VI's, confidential...):

Only the part in the middle is of interest. Both sessions are initialized and handled parallel, triggering too. This has led to some delays in the signals and should now be fixed. That aside the VI works very well.

The goal is to trigger only on one channel but both devices! If possible the device to be triggered should be chooseable.

I started rebuilding the VI using the "niScope EX 5xxx Synchronization.vi" which seemed intiuitive. The result is shown in the following picture:

I tried different RTSI lines, but had no positive results. only the master channel triggered.

After that first approach I looked into the "niScope EX Multi-Device Configured Acquisition (TClk).vi" and other TClk examples which seemed to work for similar problems. The rebuild VI can be seen in the following pictures:

(Sorry, I had to use two pics..)

In this case I had no choices for the trigger lines, they would be set automatically by the TClk VI's. I did try to trigger on both devices, though. This second approach looked promising to me, but it generated an error:

"niTClk Synchronize.vi:1<append>

<B>Session index (starts at zero): </B>1

<B>Error reported by the instrument driver: </B>

No registered trigger lines could be found between the devices in the route.

If you have a PXI chassis, identify the chassis correctly in MAX, and make sure it has been configured properly. If you are using PCI devices, make sure they are connected with a RTSI cable and that the RTSI cable is registered in MAX. Otherwise, make sure there is an available trigger line on the trigger bus shared between the devices.

Source Device: PXI1Slot4

Destination Device: PXI2Slot4

Status Code: -89125niTClk Synchronize.vi:1<append>

<B>Session index (starts at zero): </B>1

<B>Error reported by the instrument driver: </B>

No registered trigger lines could be found between the devices in the route.

If you have a PXI chassis, identify the chassis correctly in MAX, and make sure it has been configured properly. If you are using PCI devices, make sure they are connected with a RTSI cable and that the RTSI cable is registered in MAX. Otherwise, make sure there is an available trigger line on the trigger bus shared between the devices.

Source Device: PXI1Slot4

Destination Device: PXI2Slot4

Status Code: -89125"

This error kept comming even after I identified everithing possible in MAX, like shown in the screenshot:

In some of the manuals they showed how to route the trigger lines in MAX, but as you can see, there are only reservation-options displayed in my MAX. Whatever I do, I just cant find any options for defining how to route my trigger signals...

In priciple it is possible to trigger instruments in different chassis, which is shown in this Guide and some others... the question remaining is can it be done with my set of components?

I understand that the use of multichassis compromises the integrity of the highly adjusted lines like star trigger etc., so the configuration has to be taken into account in some way, which my approaches did not, i knew... But there has to be a way to achieve this?! And for starters: to just get any trigger signal from one device to the other!

For any advice on the matter I would be very thanfull!

Regards

Max1744

[dansch · Accepted solution]

Hi Max,

Thanks for the detailed post and explanations of your application and requirements. You are correct in using TClk as that is the optimal method for synchronizing the 5122 digitizers. The original VI you worked with is unique to some of the legacy digitizers and does not work directly with the newer SMC-based digitizers (such as the 5122). The good news is that you can synchronize these cards in separate chassis, but it will require use of the 66xx Timing and Synchronization (T&S) cards in the master and slave chassis as shown in the guide you linked. These are required because a common reference clock must be shared between them as well as a couple of trigger lines. MXI itself cannot handle exporting triggers and clocks, so there is no way to do it without physically wiring between the chassis using the T&S cards. Unfortunately, regardless of which specific method you do use for synchronization, it will require some additional hardware beyond what you currently have.

Since one of your requirements sounds like it is necessary to keep from wiring anything between the chassis directly, you may need to consider performing some synchronization using 1588 or GPS protocols. 1588 protocol is a network-based synchronization scheme whereas GPS obviously uses antennas and locks to a common wireless signal. While these synchronization methods may allow you to keep your chassis isolated, they will also require some manual configuration as you would no longer be able to use TClk synchronization and so the level of synchronization that you may obtain between the cards may not be as good as being able to physically wire signals between the chassis using T&S cards.

Hope this helps, 

[Max1744]

Hi dansch,

thank you very much for the clarification here!

Just to be perfectly clear: when you said "The original VI you worked with..." you meant the first example I used? ("niScope EX 5xxx Synchronisation VI")?

I guess that GPS might be not exactly what I'm looking for as a solution, but nice idea anyway 🙂

Maybe I will just go and wire the stuff, maybe the EMC isn't as bad after all...

Regards

Max1744

[dansch]

Hi Max,

Somehow I missed your reply last week. I agree the GPS or 1588 is a bit of a stretch, but I am just not sure there are any other options for completely isolating the chassis. And yes, I was referring to the original "5xxx Synchronization" VI when I mentioned it was meant for legacy devices. 

Best Regards and Best of Luck!