Why can't I read data from serial port COM1 with Labview?

[skeezer]

I have a Mettler Balance attached to COM1 via an RS232 cable.  I have a labview VI which runs but does not recognize signals from the balance, I get a reading of zero whether on not the balance is attached. I use signal conditioning SC2311 which is device 1.  How do I indicate to Labview where to find the data coming in over COM1?

[SteveChandler]

You simply indicate to LabVIEW with the VISA resource name. You have to configure the serial settings using Visa Configure Serial Port.vi.

There are so many variables that can prevent you from communicating. You have the port settings and you also have the cable. Do you have tx connected to rx and rx connected to tx? The best way to start is by not using LabVIEW but use something like Hyperterm or Putty first in order to verify everything works. Once you verify the settings you can implement the LabVIEW code.

[Dennis_Knutson]

I have no idea why you mention the signal conditioning module since it would have nothing to do with an instrument connected to a serial port.

Verify that you are using the correct com settings (baud rate, parity, etc.) and that you have the correct type of serial cable (null modem or straight-through). It is also helpful to test basic communicaiton with a terminal emulation program such as Hyperterminal, Procomm, TeraTerm, etc.