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?
> 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
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
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 ??
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.
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.
One of the different points than GPIB is you need add LF or CR/LF code to command strings, such as "F1\n".
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 > >