VISA Read- error -1073807339?

[IBAHKA]

I think that VISA is not reading anything from my serial port.  I am
using the Polhemus via serial, yet I have not been able to read
ANYTHING from the device.  Do I have to write a driver before I will
be able to read?  I am using VISA open, read, close and I am trying to
use timeout, but I don't think I am doing that properly.  Please help!
Thank-you!

Re: VISA Read- error -1073807339?

[JoeLabView]

Hi Ibahka,

Don't despair..  Serial communication is typically simple.

From your description, it appears that you are implementing correct
steps.

First question is what version of LV are you using?
What OS are you using.

I will assume Windows.  If so, are you able to communicate with the
device using HyperTerminal or some sort of communication software
outside LV?

If you were successful, are you using the identical configuration for
the way you setup the port in LV?

If you are using LV6.1 and older... I seem to remember that the
reference to COM1 was 0 (zero) and COM2 was 1.  That was a bit
confusing.

I am trying to remember what else could prevent communication...

As far as having to write drivers, not from LV point of view.
Typically, whoever designs the product and offers the serial
communication port already has their drivers and set of commands
available.

The 1st thing is to be able to communicate with the device using
someting like HyperTerminal.  Once that works, the rest is simple.

Other possibilities could be the RS-232 cable.. verify the cable.

Good luck,

JLV

Re: VISA Read- error -1073807339?

[Dennis Knutson]

You are creating a LV driver when you use the VISA functions. Joe's
suggestion to try it in Hyperterminal is a good one. I noticed that
you do not mention either VISA Configure Serial Port or a VISA Write.
Once you verify baud rate, stop bits, etc. and the cable with
Hyperterminal, you should put in a VISA Configure Serial Port with the
same settings as Hyperterminal. If the instrument sends out a constant
stream of data (which you can confirm in Hyperterminal), then you
don't need a VISA Write to tell the instrument to send something. If
it doesn't, you'll have to first write that command and then do a
read.