Brooke:
When using a VISA property node, it requires LabVIEW to open a VISA session
to the resource of interest. The act of opening a VISA session to a serial
resource will cause NI-VISA to assert both the RTS and (as long as it's not
a 485 port) DTR. If you close the VISA session at the end, or if you have
LabVIEW configured to auto-close VISA sessions when your VI stops, then
NI-VISA will deassert RTS and DTR (even if it's a 485 port) when it closes
the port.
This NI-VISA behavior is expected and standard behavior across all
platforms. Most other serial utilities or drivers will automatically
assert these lines on open and deassert on close, so VISA isn't doing
something unique.
Dan Mondrik
National Instruments
Brooke Clarke
<[EMAIL PROTECTED] To: Info-LabVIEW Mailing List
<[EMAIL PROTECTED]>
et> cc:
Sent by: Subject: Details on use of Device
Control/Status.vi
<[EMAIL PROTECTED]
a.army.mil>
04-01-2004 01:03
PM
Hi:
A number of people have told me that using the VISA Property Node.vi is
the way to go. It appears to have more functionality than the Device
Control/Status.vi.
The VISA Property Node.vi does allow control of lines as expected, but .
. . . when reading the status of a line that line's status is changed.
I was not expecting that.
I have a very simple sequence with frame 1 having a single VISA Property
Node with two elements that sets RTS and DTR.
Frame 2 has a 3 second wait.
Frame 3 has another VISA Property Node with 4 elements to read the
status of CTS, DCD, RTS and DTR.
When I run this I can see DTR change for 3 seconds then change back to
where it started.
Any thoughts on how to check status without changing it? Or do I need
to do another set status using the read result as it's input. That
seems like a kludge.
Thanks,
Brooke Clarke, N6GCE
Subject: Details on use of Device Control/Status.vi
From: "Brooke Clarke" <[EMAIL PROTECTED]>
Date: Wed, 31 Mar 2004 11:19:29 -0800
Hi:
I'm writing an application where I need to be able to bit bang serial
port output lines and check the status of serial port input lines in LV
5.1.
In the vi.lib\instr\_sersup.llb folder there is the serial line
control.vi and it uses two sub VIs to allow controlling the DTR and RTS
lines by using the "open serial driver.vi which can be opened and
figured out plus the Device Control/Status.vi which is a yellow vi and
can not be opened.
I have the feeling that with the proper inputs to Device
Control/Status.vi it would be possible to read the status of the serial
port input lines CTS and DCD.
Does anyone have details on using the Device Control/Status.vi?
Thanks,
Brooke Clarke
Rack and Stack Systems
(800) 700-TEST = 800 700-8378
