How to sync mutiple PXI RT controllers

[LarryReding]

I have three independent RT PXI chassis each with a 8071 controller, each will be acquiring data and performing motion control. What would be the best way to sync all the motion and acquisition applications on each system.

[russellb]

Hello,
It sounds as though you want each one of your programs running on each independent RT PXI controller to start in software at the same time. I would suggest using TCP/IP commands between the PXI controllers. However this will not be deterministic, therefore I must ask how closely do you want your programs to start together?

Regards

Russell Blake
Applications Engineering
National Instruments

[Ben]

Hi Larry,

This topic intrests me but I have had an opertunity to do one of these yet.

As mentioned in the other answer, we need to know "How close the sync the to be".

I can only throw out two ideas.

1) CAN bus is supported under RT and has deterministic mode.

2) TCP/IP and hardware combo. Run a single sync signal to all of the RT systems and use it to clock all of the systems. Use TCP/IP to let each RT system know it should set up its I/O and start watching for the sync.

I would like to know what approach ends up working for you.

Ben

[LarryReding]

Ben

The answer to how close of a sync do we need is something between 500 to 100 ms.

Right now my ideas are everyone start & stop on an event say a TCP/IP or UDP message. All the chassis have PXI DAQ modules and using DIO lines is another approach.

With this said I was wandering if there is a PXI bus line that may be used. I looked at the pin out and description of the PXI bus but nothing jumped out so I just wanted to make sure I have not missed a PXI bus or module option.

Thanks
Larry

[LarryReding]

The answer to how close of a sync do we need is something between 500 to 100 ms. The sync I am intending is between processes running on each system
not so much as software starting and stoping.


Right now my ideas are everyone start & stop on an event say a TCP/IP or UDP message. All the chassis have PXI DAQ modules and using DIO lines is another approach.


With this said I was wandering if there is a PXI bus line that may be used. I looked at the pin out and description of the PXI bus but nothing jumped out so I just wanted to make sure I have not missed a PXI bus or module option.


Thanks
Larry"

[russellb]

Hello,
If you have multiple PXI DAQ board you can send a trigger pulse from a master board to a slave PXI DAQ board through RTSI for one chassis. Then send a trigger pulse across a PFI line from a slave in the first chassis to a PXI DAQ board in the second chassis.

Regards

Russell Blake
Applications Engineering
National Instruments

[LarryReding]

We have added a PXI-6602 to each of the chassis they will be used primarily for encoder monitoring. So can we use PXI-6602’s with the PFI lines? Also what a good source to get educated on PFI lines.

Thanks
Larry