4-20ma output of ph controller connection to pc to monitor

[Skegsy]

I have a PH probe /contoller with 4-20 ma output for input into a pc for monitoring purposes , Now 4ma being 0 Ph and 20ma being 14 Ph , Can I simply wire this into to a comm port on my pc rs232 and then use labview too monitor and perhaps control.Any help greatly appreciated.

[Dennis_Knutson]

No, you can't. An RS-232 port is not an analog to digital converter. You would have to use some sort of daq board.

[Bill B]

Hello,

Unfortunately, the RS-232 port cannot measure an analog current or voltage. We do carry products which will allow you to measure such signals. Please take a look at our Data Acquisition boards. Our boards are able to read analog voltages. You would simply need to connect your current to a resistor and then measure the voltage across the resistor with one of our DAQ boards. Here is a link to our DAQ boards:
http://sine.ni.com/apps/we/nioc.vp?cid=1037〈=US

Please let me know if you need any help selecting a board for this type of measurement. Note that these boards have multiple channels that you would allow you to monitor multiple sensors simultaneously in LabVIEW.

Regards,
Bill B
Applications Engineer
National Instruments

[Skegsy]

Thanks everyone for the advice ,I have decided to use an old datataker dt50 I have ,But am unsure how to use labview to monitor these sensor readings, Does anybody have any advice or know were to get labview drivers for this device , Any help appreciated.

Regards
Brett Scott

[Bill B]

Brett,

I looked at the specs for the datataker dt50 and I noticed that it has a serial port interface. You may be able to send commands to the dt50 from LabVIEW and the dt50 may respond with data. You will need to get the command set from datataker. Here are some links to tutorials that explain getting started with serial programming:

http://zone.ni.com/devzone/devzoneweb.nsf/Opendoc?openagent&14A5CB349BD18D20862568210005EB0A#2
http://zone.ni.com/devzone/conceptd.nsf/webmain/C553228FD78A7ADD862568F9006E9129?opendocument
http://zone.ni.com/devzone/conceptd.nsf/webmain/D48BA43C59B60277862569EE000501FD?opendocument

There are also some good serial communication examples that ship with LabVIEW. Go to Help >> Find Examples >> Hardware Inpu
t and Output >> Serial

Regards,
Bill B.