Problems with access to serial port using reentrant code

Question

Hi,
I have a VI that send commands and receive answers from an instrument using
de serial port.
This VI runs perfectly when used alone.
However I'm trying run two instances of that VI simultaneously using
reentrant code and I'm facing some problems.
Sometimes everything is OK but sometimes, in the process of writing to
serial port the following error happen:
Error code 36.
Invalid refnum device.
What is this?
Does someone know how to prevent this?
Thanks in advance for any help.

Answer 1

"Paro, Paula [CMPS:2721:EXCH]" wrote:
>
> Hi,
>
> I have a VI that send commands and receive answers from an instrument using
> de serial port.
> This VI runs perfectly when used alone.
> However I'm trying run two instances of that VI simultaneously using
> reentrant code and I'm facing some problems.
> Sometimes everything is OK but sometimes, in the process of writing to
> serial port the following error happen:
> Error code 36.
> Invalid refnum device.
>
> What is this?
> Does someone know how to prevent this?
>
> Thanks in advance for any help.
You can't use reentrant vi's vith serial vi calls without supervising of
driver.
Use VISA instead and you have to control the VISA session opening and
closing. Another word is that the only one serial port sess
ion should be
opened at a time.
Reentrant vi's for serial port without checking serial port session is a
mistake of program algorithm. Change it in any convenient way.
Sergey Krasnishov
Automated Control Systems
National Instruments Alliance Member
Moscow, Russia
[email protected]
http://acs.levsha.ru