LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

serial-port read

Hello,

I´m using a digital multimeter to serial port (COM1) connection to get
0-100 mV´s from a photomultiplier, but it doesn´t work. I used the
LabView-Serial Port VI in the read-mode. The VI proceed´s but it doesn´t
put out any data.
Did I use the right VI?

Can anybody help me?

Thanks

Oliver
0 Kudos
Message 1 of 8
(3,037 Views)
Oliver wrote:

> Hello,
>
> I´m using a digital multimeter to serial port (COM1) connection to get
> 0-100 mV´s from a photomultiplier, but it doesn´t work. I used the
> LabView-Serial Port VI in the read-mode. The VI proceed´s but it doesn´t
> put out any data.
> Did I use the right VI?
>
> Can anybody help me?
>
> Thanks
>
> Oliver

This is the right VI. You may have to send a command to
the meter to make it put out data. I really dont have enough
info from your post to be more specific.
Kevin Kent
0 Kudos
Message 2 of 8
(3,037 Views)
You will need to initialize your port first with the Serial Port Init.vi and
if
you are trying to read more bytes than your device is sending you won't
get any data. Put the Bytes at Serial Port.vi "ahead of the Serial Port read
vi.
and wire the Bytes at Serial Port value byte count to the Serial Port read
input value
requested byte count. Also, labview com 0 is com1 on the PC. Hopes
this helps
0 Kudos
Message 3 of 8
(3,037 Views)
I found some info about the Multimeter:
I´ve got two possible modes to get data from the DMM
1. by using send-code:
M: DMM sends stored data
C: DMM resets stored data
😧 DMM sends display-data

2. without send-code
if the COMM-button off DMM is pressed, DTR has to be set to Lo by PC. DMM will

send display every second

transferrate is 1200 baud
charakter code 7-bit ASCII
no parity
stop-bits 2
length of string 14 byte

I also found a short MS-Quickbasic-file:

CLS
OPEN "COM1:1200,N,7,2,RS,CD,DS,CD" for INPUT A$
INPUT #2,A$
PRINT A$
CLOSE #2
END


I used the serial-communication VI this time in order to give the DMM
commands ( M,C,D) but the DMM didn´t answer. I set the
data-communication-parameters in the sub VI´s, maybe that was the fault. Have
you got any idea
what´s wrong??
To what, in your opinion do the characters RS,CD,DS,CD in the "OPEN COM1
command-line stand for ??

Thanks, for your help,

Oliver
Message 5 of 8
(3,037 Views)
Oliver-

The QuickBasic commands RS ... etc are for configuring low level serial communication
lines(ready-to-send, etc). The Quickbasic code you have will only read data
from your DMM.

I recommend first setting your DMM to send data every second, and using the
Read Serial with Timeout.vi to get one-way data out of the DMM. After you
successfully debug getting data out of your DMM from LabVIEW, then sending
info to the DMM will be somewhat easier.

After you successfully get data from your DMM, you can follow suggestions
from earlier postings regarding CR/LF and other issues.

Good luck-

Farrel
0 Kudos
Message 6 of 8
(3,037 Views)
Hallo, Oliver,

Du meintest am 05.04.00 zum Thema Re: serial-port read:

> 2. without send-code
> if the COMM-button off DMM is pressed, DTR has to be set to Lo by
> PC. DMM will
>
> send display every second
>
> transferrate is 1200 baud
> charakter code 7-bit ASCII
> no parity
> stop-bits 2
> length of string 14 byte

Sounds like the Metex-/Conrad-DMM. May be there is a *.vi in the NI-
filebase.


Viele Gruesse!
Helmut
0 Kudos
Message 7 of 8
(3,037 Views)
Helmut Hullen schrieb:

> ........
> Sounds like the Metex-/Conrad-DMM. May be there is a *.vi in the NI-
> filebase.
>
> Viele Gruesse!
> Helmut

Few years ago I got a METEX driver from Thijs Bolhuis,
t.bolhuis@el.utwente.nl

See attachment


Franz
0 Kudos
Message 8 of 8
(3,037 Views)
One of the different points than GPIB is you need add LF or CR/LF
code to command strings, such as "F1\n".

Makoto

Oliver wrote in message
<38E8A63B.70A326E4@biophysik.biologie.uni-mainz.de>...
>Hello,
>
>I$B%((Bm using a digital multimeter to serial port (COM1) connection to get
>0-100 mV$B%((Bs from a photomultiplier, but it doesn$B%((Bt work. I used the
>LabView-Serial Port VI in the read-mode. The VI proceed$B%((Bs but it doesn$B%((Bt
>put out any data.
>Did I use the right VI?
>
>Can anybody help me?
>
>Thanks
>
>Oliver
>
>
0 Kudos
Message 4 of 8
(3,037 Views)