Synchronizing of Two myRIO FPGAs

[AhmadHassan]

Hi people,
     I am using two myRIO FPGAs to get the 50 digital outputs and I want to synchronize these two myRIO FPGAs. Is it possible to make a single VI to control the both FPGA targets? I have made the single project and have added both FPGA targets. Now, I want to run both the FPGAs at the same time and want synchronization between them. How can I do this?
Kindly help! 

[Bob_Schor]

Wow -- I was unaware that a myRIO had two FPGAs.  Or maybe you mean that you want to synchronize two independent myRIOs ...  If you had compressed the file containing your Project and attached the resulting ZIP file, we could see what you have done and made (probably helpful) suggestions ...

Bob Schor

[AhmadHassan]

Yeah, I mean, I want to synchronize two independent MyRIOs. 

[algarcia]

Hi Ahmed,

Since the myRIO wasn't designed with synchronization to multiple RIOs in mind, this may be difficult. 

How tight of synchronization are you hoping to achieve?

One method that may work, would be having individual VIs running on each myRIO and having one sample and write a digital signal on a Digital Out line to generate a sample clock. This sample clock would then be read on a Digital Input line of the 2nd myRIO and then have it sample whenever it receives a digital high on this line.

Alternatively, the cRIO or cDAQ platforms are much better suited for synchronization. 

[AhmadHassan]

Hi Alex G.,
     Thanks for giving your thoughts. Yes, I have tried to synchronize two myRIOs by using digital lines but unfortunately, it didn't work out. Through this procedure, both myRIOs give their output at the same time but after some time, one myRIO get unsynchronized with the other. I don't know, what should I do to keep them synchronized.

[algarcia]

To reduce the drift in synchronization, you could try wiring an external oscillator (digital signal clock) to have them operate on the same signal.

However, since these devices weren't intended for this type of behavior, different hardware would be the best solution.

[AhmadHassan]

Alex G.,

Can I import an external Oscillator Clock on myRIO? I mean, can I drive the SCTL by the external clock?

[algarcia]

Ahmed,

The myRIO is unable to drive a SCTL with an external clock. Please refer to the following thread regarding this issue:

https://forums.ni.com/t5/Academic-Hardware-Products-NI/Want-to-use-external-clock-for-SCTL-on-myRIO/...

Best