Missing characters of a string in TestStand

[Applications in LabVIEW FPGA module]

Hi
I am facing problems with the TestStand Sequence. The VI transmits a string from the NI-7831R RIO using FPGA VI to the COM1 Serial Port.

I am integrating a LabVIEW VI into teststand. The VI has two parts.
1. FPGA VI
2. Host VI
The FPGA VI sends a string, character by character at the specified baud rate, parity bit, data bits and stop bit setting from the NI-7831R RIO to the COM1 Serial Port of the PC. The COM1 Port receives the string at the same configuration setting. The Host VI just displays the string form the VISA Read Function. This works properly in LabVIEW, but when i integrate this to TestStand by making the DLL, i am getting only alternate characters(odd characters) as my output!!!
For instance,
if my input string that is to be transmitted from the FPGA is "TEST", then i read it from the VISA Read function as "TS"

I have attached the FPGA VI, Host VI, the Sequence file and the Screen shots of the error.

Please look into the attahced files and help me to solve the problem.

Regards,
Subramania Bharathi

[Shannon R]

Subramania,

TestStand shouldn't affect the data transfer between your COM port and LabVIEW. From the screen shots, this does seem like a very odd behavior. I would recommend debugging this from TestStand and stepping into the VI to make sure that the value sent over the COM port is the same that is being displayed.

If you continue to see this behavior, try to cut out just the code that reads over the COM port and we'll see if we can help with that small VI.

Let me know what you find out.

Regards,
Shannon R
Applications Engineer
National Instruments