Synchronization of signal

[Moni98ce]

Hi,

Is there any way to synchronize signals that are collected in HOST PC and NI CDAQ? I am collecting encoder signal in the Host PC from the ACR-9000 controller and at the same time, I am collecting the load cell data by using NI controller cDAQ-9137 (C series NI-9237). Could you please guide me or provide me with any references? I appreciate your support. Thank you.

[santo_13]

Depends on your definition of synchronization - seconds, milli seconds or microseconds.

Software level synchronization is limited by your OS and time taken for you to read data. Hardware-level synchronization gives your best accuracy and precision but your hardware needs to support that.

[Moni98ce]

Hi Santhosh,

Thank you very much. My loop time is 4ms. The operating system for Host PC is Wndows 10.

[santo_13]

4ms may be achieved by OS timing but NOT GUARANTEED. Find out if both your hardware can have some way of external electrical synchronization.

[Moni98ce]

Hi,

I do not have any idea about that. Could you please give me some idea about that. Do you know how can I do that in the current hardware configuration?

Thank you.

[GerdW]

Hi Moni,

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@Moni98ce wrote:

Is there any way to synchronize signals that are collected in HOST PC and NI CDAQ? I am collecting encoder signal in the Host PC from the ACR-9000 controller and at the same time, I am collecting the load cell data by using NI controller cDAQ-9137 (C series NI-9237).

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How do you read data from the ACR9000 controller? Which communication bus is used? RS232, Ethernet, USB, CANopen? Does that controller allow external sync/trigger signals?

The NI9237 uses its internal timebase and is able to export its timebase or to take an external timebase. Importing/exporting timebases has to be routed through the cDAQ9137 chassis. That chassis also maintains its own timebase clock. To export that timebase/clock signal to allow triggering external device you might need to use an additional DIO module (I'm not an expert in cDAQ devices).

So before we can answer all your questions you need to read some manuals on your own and you need to provide much more information on your specific setup!

[Moni98ce]

Hi GerdW,

Thank you very much for your reply. I am using  Ethernet communication for the ACR controller. I am attaching the picture of the VI that I am using in the Host PC to read the data from the ACR controller. "Does that controller allow external sync/trigger signals?" I am not sure about it. I am trying to learn this. 

Thank you.

[Moni98ce]

Hi Good people,

I developed the VI (attached here) by following this link (Figure 6 and 7 for 2 DSA modules),

https://www.ni.com/en-ca/support/documentation/supplemental/21/signal-based-synchronization-of-analo....

I used a 2 Hz input signal to check my code and perform the FFT of the measured force (from without mean and filter case) and observing the result as this figure. I do not know what wrongs with my program. Could anyone check my program and guide me? 

Thank you in advance.

[dsb@NI]

The DSA device must provide the timebase source for synchronization. What two modules are you using? If these modules can sample at the same rate, check to see if your channels can be added to the same analog input task and try synchronization by channel expansion. Let us know how that goes!

[Moni98ce]

Hi Doug, 

Thank you very much for your reply. I am using NI 9234 and 9237 modules and  NI cDAQ 9137 chassis.