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CAN + analog signal time synchronization

Hello, 

 

I am trying to use Flexlogger as a simple data acquisition device for the following scenario:

 

- 1 laptop running Flexlogger and our proprietary software.

- signal sent via CAN from laptop to controller (proprietary controller on CAN bus)

- measuring current output from controller into flexlogger via analog input with current shunt

- current feedback being sent back to controller via CAN (for controller current servo closed loop control)

 

Our goal is to have time-synchronous data with these 3 signals such that we can see command and feedback on CAN, along with a ~10kHz sampling of our analog PWM.  There are also a number of additional CAN signals and a few more analog signals.

 

The problem I am seeing is that the aforementioned CAN signals are out of sync with the analog signal by varying amounts ranging ~ +/- 300ms.  I cant get a bead on any factor on my end that has influence over this - it seems random.

 

Hardware used is listed below:

cDAQ 9174 - chassis

NI 9215 - used for high frequency analog inputs

NI 9860 + TRC 8542 - CAN card + transceiver cable for CAN inputs

 

Picture illustration of the problem is attached.  Any thoughts would be appreciated.

 

 

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