cDAQ 9174 multiple modules time offset

[bezoky]

Hi,
Im experiencing time offset for data from two different modules in my cDAQ 9174.
NI9205 - analog input module - reading 1 proximity sensor (measuring moving mass position)
NI9237 - bridge module - reading 2 force sensors (1st works as makeship accelerometer, 2nd reads force exerted by motor)

Im not using producer-consumer because logging times are short (20000 rows of data at maximum).

1) sample rate 2500Hz for both tasks because of NI9237 clock shenanigans
2) data comming from NI9205 have roughly 0,1sec latency 

3) mechanical setup scheme attached
4) VI attached (LW version: 16.0f5 64bit)

Thanks for your help.

[dr2]

bezoky,

Synchronizing two modules that work so differently is always a challenge.  The 9205 is a multiplexed input module - i.e. there is only one A/D converter & the 9237 is a simultaneously sampled module with a input filter delay.

I would suggest one of two approaches:

Either use a voltage divider on your proximity sensor to get the signal level down to the right range for the 9237 and just use the one module.

Or get a function generator and generate a signal into the two modules simultaneously and work with the DAQmx driver until the two signals lineup as desired.

-Dave

[ZYOng]

NI-9205 uses SAR ADC whereas NI-9237 uses DSA.

See Figure 10 of Signal-based Synchronization of Analog Input C Series Modules