RS422 packets missed when transmitted at repetition rate of 15ms

[Mahboob_ur_Rehman]

Hi,

I am trying to send RS422 serial packets using NI PXI 8431/4 module. My goal is to send serial frame repetitively at 15ms interval, but sometime the packets are missing as they don't occur at next 15ms interval.

I have placed serial transmission VI inside a while loop and added a "wait ms" function to set the loop timing to 15ms.

Can you please guide me how to achieve desired repetition interval?

Thanks,

M Mahboob

[Albert.Geven]

You best use a timed loop instead of a normal while loop and not use a wait ms in that loop anymore. 

[crossrulz]

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@Mahboob_ur_Rehman wrote:

I am trying to send RS422 serial packets using NI PXI 8431/4 module. My goal is to send serial frame repetitively at 15ms interval, but sometime the packets are missing as they don't occur at next 15ms interval.

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How large are your packets and what baud rate are you using?  What controller are you using and what OS is it running?  How accurate do you need that interval to be?

[Mahboob_ur_Rehman]

Sorry, I should have mentioned the details earlier. 

1. Packets lenght is in range of 2-3ms aproxx

2. Baud rate= 38400

3. Pxi chassis with embedded controller running Windows OS

4. Accuracy required is in mili seconds, desired is 15ms

Thanks,

M Mahboob 

[Mahboob_ur_Rehman]

PS:

The chassis is PXIe-1071

Controller is PXIe-8821