sbrio-9627 serial rs485 write speed is slower than sbrio-9626

[Samuel_James]

Since sbrio-9626 is obsolete so i am migrated the code to sbrio-9627. 

After migrating the code from i found out some issues with serial write. Serial write is not working as expected its not throwing error but i couldn't get the right data from the serial port. after several trouble shooting i found serial write speed in sbrio 9627 is much slower than its predecessor sbrio 9626. Increasing the baud-rate is fixing the issue but in my case 38400 was as default. i have attached the test vi which i used it for testing on both 9627 and 9626. The below screenshot shows the write performance. For the same string length 9626 can write at 22Hz while 9627 writes at 18Hz. I knew both are running different OS but i don't think its because of that. Is there any minor tweak to increase the performance of sbRIO 9627.

Thanks in advance 🙂

Regards,

Sam

[Riley_Ilieva]

Hi Sam, 

I'm not sure as to the solution to this as the specs of the two are very similar, but I have a couple of clarifying questions:

1. You mentioned there is no error, but the resulting data was incorrect. How so? 

2. How does this lower rate impact your project? Is there a speed requirement that is not satisfied by the 9627? 

Kind Regards, 

Riley Ilieva

Applications Engineer

National Instruments

[Riley_Ilieva]

Hi Sam, 

After having taken a more detailed look at this, there a big difference between the 9626 and the 9627 - the OS. The 9626 is VXWorks and the 9627 is LinuxRT which can cause some differences. 

See picture below for information on the VISA Write Function 

Could you possibly tell us what result you get for each mode on each target at the desired rate? 

Additionally, could you possibly send a MAX report of each target? 

Kind Regards, 

Riley Ilieva

Applications Engineer

National Instruments