I have read various SU questions, but didn't find this. I have four COM ports, RAW Serial COM ports, not USB, COM1-4. If I connect a serial cable to the machine and connect the other end to the serial device (no USB, no Ethernet, regular old RS232), which COM port do I use?

Does it matter which COM port I use, if I only have one Serial device attached? I am using PuTTY.

  • Which COM port is used depends on which one of the ports is COM1. Have you checked the motherboard for a diagram layout which most of the time indicates which port was COM1? – Ramhound Sep 14 '17 at 19:17
  • This depends more on the software driving the device. Just try them all. – harrymc Sep 14 '17 at 19:30
  • @Ramhound No. I will see what I can do. It is a laptop. – johnny Sep 14 '17 at 21:32
  • @harrymc That will not help me because the device may or may not function correctly. I have tried them all. That is why I wanted something more definitive. – johnny Sep 14 '17 at 21:33
  • If you have tried them all without success, then there is problem. This can be that you are missing the driver to recognize the device, so check for an unknown device in Device Manager. It can also be defective COM ports, so try on another computer. Or the device itself is dead. – harrymc Sep 15 '17 at 6:18

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