Synchronise READ from Serial card when Counter on 6025 is incremented

Hi!
System description:
I am using PXI-8423 (2-port RS-422) and PXI-6025 to measure the signal coming from 2 laser sensors mounted onto a mechanical stage with linear encoder.
The laser sensors give RS-422 output (at 1KHz) and are connected to my serial card.
The encoder gives quadrature output that I plan to connect to counters on my 6025 daqcard.
Q:
I want to read the laser data everytime the encoder gives a pulse signifying the mechanical stage has moved. How can I achieve this?
We would be taking around 1000 serial reads (from each port) per second.
Environment:
We are using PXI-1031 chassis (4-slot) with PXI-8184 controller (850 MHz celeron). OS is Win2K prof. and LabVIEW 7.1
Thanks,
Gurdas
[email protected]
Gurdas Singh
PhD. Candidate | Civil Engineering | NCSU.edu

Hi Gurdas,
We have some simple serial communication examples included in LabVIEW. Those example programs transmit any string of characters over the serial port. All you have to do is set which port you want to use, baud rate, stop bits, parity, etc. in the VI; this setting wil remain for each serial transfer while the program is running. Again, you can read/write any character string with the serial communication VI's. How the information is put into the character strings is up to you and the device you are communicating with. The serial communication is LSB before MSB.
Regards,
Salvador Santolucito
Applications Engineering
National Instruments
Attachments:
Basic_Serial_Write_and_Read.vi ‏66 KB
Advanced_Serial_Write_and_Read.vi ‏105 KB

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"Francesco83" ha scritto nel messaggio
news:[email protected]..
> Hello, I am a student trying to develop a Labview VI that talks with
> TDK blue2i module (with at style commands) via serial port, just like
> Hyperterminal.My VI consists of a while loop, inside of that I do VISA
> write, then VISA read using Bytes at serial port since answers are
> variable in lenght. When i run the program the first loop works ok (
> i send message and get the right answer ) but in the second loop i
> still read the fisrt answer even if send a different command.
> Is there a way to make sure that buffer of the serial port is cleared
> after every reading?
> Sounds like a timing problem, Everything works well if I run the
> progra
m Step by Step
>
> thanks
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Synchronise READ from Serial card when Counter on 6025 is incremented

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