I have an old lab device which prints it's result to a serial printer. I need to replace the serial printer with a computer. I have connected the device's 9 pin serial port to the computer's serial port, and started hyperterminal with the connection setting as described in the manual. The settings are as follows:

  • Printer interface
  • V.24 ( RS 232 C )
  • 9600 baud
  • 1 start bit
  • 7 data bits
  • 1 parity bit
  • 1 stop bit
  • output only, no control lines.

For some reason hyperterminal does not display any result from the unit. Is there something I am missing? Do I require a special serial cable? If I can get the result in Hyperterminal, I would be able to develop my C# program.

Thank you for your assistance.

  • This is a hardware issue, not a programming issue. Stackoverflow is the wrong place for this question.
    – Daniel Mann
    Nov 28, 2012 at 22:34
  • I have previously communicated with other serial devices with c#. For some reason I cannot read the output from the device which is meant for a serial printer. Thus I believe it is either a communication port setup, physical cable setup, or some communication which must first be send to the device to let it know it can transmit. Nov 29, 2012 at 5:07

3 Answers 3


Have you tried a null modem cable? It's a cable that has RX/TX cross connected. A pinout should be published somewhere.

  • Thank you for the reply. I have purchased a serial data cable from our local pc store. Would that be a null modem cable, or must I ask specific for it? Nov 29, 2012 at 5:09

I think what you're after is a Null Modem cable. You may have trouble finding one any more though.

  • Thank you for the link; I will use the information to ask the pc shop to make up one for me. Nov 29, 2012 at 5:13

If you are trying to simulate a serial device, you could try com0com to set up a virtual serial port.

  • Thanks you for your help. I have downloaded it, and will test it today. Nov 29, 2012 at 5:11

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