NI 9237 delay with NI 9205

[Leedaqbook]

Is there any way to correct the time lag or gap between NI-9237 force and NI-9205 Volt on CompactDaq-9188?

The delay is because ni-9237 has 24 bits resolution and ni-9205 has 16 bits resolution.

[Supertramp]

Hello Leedaqbook, I would like to know more information about what are you doing... How are both devices interconnected and in which kind of function they have the delay?  

Regards

[Leedaqbook]

I have a VI to record data of load cell and voltages and running a cDAQ-9188 with NI-9237 and NI-9205.

Checking the record i can see a delay in NI-9237 data.

Can I eliminate this delay ( NI Document ID : 5PBC0FS1) with VI to synchronize NI-9205 data

[JuDa]

Hi Leedaqbook,

Could you share with us your VI so we can analyze your application? Are you synchronizing your acquisition via SW or HW. If you want to take measurements synchronized from both modules my advice would be to use the same Base clock for both your modules so you can receive the same measurements. You will need to acquire at the same sampling rate otherwise your NI 9205 acquires at 250KS/s and the NI 9237 at 50KS/s. It would be very difficult to see in a chart the time delay of the ADC conversion time. 

Synchronize Strain Gage & Voltage Measurements with cDAQ Chassis

DAQmx - Synchronized AI/AO Shared Clock - LabVIEW - CVI - ANSI C - C#.NET - VB .NET    Synchronize Clocks

Synchronizing Multiple DAQ Devices

If you have any other questions please let me know

Best Regards,

[DamBos]

Check the manual of NI 9237 (http://www.ni.com/pdf/manuals/374186e.pdf) and on page 25 you can read:

»input delay ….. 38.4/fs + 4.8 us«

So you have a constant delay on NI9237 which can be calculated by using the correct value of the sampling rate (fs) that you are using. So then you can manipulate with the output signal and synchronize both (or more) signals.

(if I'm not mistaken the delay should be around 20ms for one of the lowest data rates possible on NI9237)

p.s.: as you probably have both AI signals inside one single task and on the same chassis then you don't have to worry about synchronization. If you use multiple tasks (like AI and DI task) even if the cards are on the same cDAQ chassis then you have to use start triggers.