Check for Serial Break Status ?

[rulerich@my-deja.com]

I've got a custom instrument that my research
lab uses in-house. We've been using our own
crude programs to read in data from it, but
we're looking to migrate to LabVIEW.

Each set of data points contains 9 bytes of
data that are read through the serial port.
So that it is possible to figure out one's
location in the 9 byte pattern (since otherwise
they all run together) the instrument transmits
a break.

I cannot, for the life of me, figure out how
to get LabVIEW to read the break through a VISA
session. I could use the In Port VI to read in
the port status byte (0x3fd for the generic
COM1), but I'm trying to make it so that non-
standard ports are supported.

I'm fairly sure that I'm overlooking something in
the VISA prop
erty node, but I'm not sure what.

Thank you for your time,
Rhys Ulerich


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[dan.mondrik@natinst.com]

Rhys:

Unfortunately, you aren't missing anything. VISA doesn't support that
feature currently, and to be honest, we weren't planning to add any new
serial functionality in the next release. It sounds as though you have
something that does work for now, so that's good. Please let me know
if this becomes a problem for you.

In article <7nlhbr$u77$1@nnrp1.deja.com>,
rulerich@my-deja.com wrote:
> I cannot, for the life of me, figure out how
> to get LabVIEW to read the break through a VISA
> session. I could use the In Port VI to read in
> the port status byte (0x3fd for the generic
> COM1), but I'm trying to make it so that non-
> standard ports are supported.

Dan Mondrik
Senior Software Engineer, NI-VISA
National Instruments


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[rulerich@my-deja.com]

I have one situation where this could be a problem, and one where it is
a problem.

The first possibly problematic situation is that I need to create a VI
for use out-of-house and I'd like to avoid requiring the user to know
the base hardware port of the serial port. While this isn't a big deal
for anyone who's messed with serial ports before, it will be for
someone who just wants to plug in the instrument and take measurements
immediately (especially for 3rd party add-on serial boards with non-
standard addresses). Is there some way to open a Serial VISA session
and then read it's base hardware address? (i.e. open ASRL1::INSTR or
whatever it is and have a VISA property node return 0x3f8)

Supposing that it is possible to return 0x3f8 when opening a
VISA
session to COM1, is it possible to use the In Port VI to read the
port's status byte without messing up the VISA session's buffer? I
don't see any reason why it would be a problem, but I thought that I
would check anyhow.

The second and definitely problematic situation is that I'd like to
make the VI portable. But from what I understand the In Port and Out
Port VIs aren't supported on any platform besides that of the x86
running MS OSes.

Thank you for your time,
Rhys Ulerich

> Unfortunately, you aren't missing anything. VISA doesn't support that
> feature currently, and to be honest, we weren't planning to add any
new
> serial functionality in the next release. It sounds as though you
have
> something that does work for now, so that's good. Please let me know
> if this becomes a problem for you.
>

> > I cannot, for the life of me, figure out how
> > to get LabVIEW to read the break through a VISA
> > session. I could use the In Port VI to read in
> > the port status byte
(0x3fd for the generic
> > COM1), but I'm trying to make it so that non-
> > standard ports are supported.


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[transam73@hotmail.com]

In article <7npvm7$qnb$1@nnrp1.deja.com>,
dan.mondrik@natinst.com wrote:

>Unfortunately, you aren't missing anything. VISA doesn't support
>that feature currently, and to be honest, we weren't planning to
>add any new serial functionality in the next release.



What is with this lame attitude against serial comms? The
VISA routines are a big improvement over the old serial stuff, but
there's still LOTS of improvement to be done. You should also
publish some better queue control. I'm really disappointed with
serial support in Labview. I'm also distressed by the bugs (i.e.
I can't seem to contact higher than COM9 even though I've
modified the .ini file to move the LPTs higher--it is apparently
ignored). We should have unlimited # of co
m ports (or at least up
to 256 or so) available. And a parallel port is not a serial port
so why kludge them together in the first place? I also noticed
that serial read vis can't be trusted to respond quickly. I made
a two-way sniffer to examine serial exchanges between two
computers, and the response bytes sometimes show up before the
query bytes on my display!

Serial support is IMPORTANT. Just because natinst isn't in the
business of making serial instruments you use it as an excuse to
neglect supporting it adequately. Adjust your attitude, please.


-O-


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