How to perform a loopback test on a RS232 system

Question

  • How do you determine which pins to jumper on DB9 or DE9 male connection serial port on a computer/desktop/laptop when performing a loopback test?
  • How to do I perform a loopback test on a USB to RS232 serial adapter?

Environment

  • Product Family: Message Displays
  • Product: Galaxy
  • Component: Serial Communication, USB to Serial adapter (e.g. Prolific, Moxa), Computer with 9 pin male serial/COM port
  • Control System:

Answers/Steps

Note:   reference  How to perform a loopback test with HyperTerminal DD1994747 for performing the loopback test.
  • Use a paper clip (or other conductor) to perform loopback and jumper pins 2 & 3 together
  • When looking at the serial DE-9/DB9 male connection, go to the column/row that has 5 pins.
  • With a USB to serial adapter, orient the adapter so that the 5 pins are on the top (more pins across the top then the bottom)

Vertical Orientation DE9/DB9

  • If the column of 5 pins is to the right of 4-pin column, then pins 2&3 will located near top of the 5-pin column (i.e. pins numbered 1-5 top-down)
  • If the column of 5 pins is to the left of the 4-pin column, then pins 2&3 will be located closest to the bottom of the 5-pin column (i.e. pins numbered 1-5 starting at bottom)

Horizontal Orientation of DE9/DB9

  • If the 5-pin row is located on top of 4 pin row, pins 2&3 will be located closest to the left on the 5-pin row (pins numbered 1-5 from left to right)
  • If the 5-pin row is located under the 4-pin row, pins 2&3 will be located closest to the right on the 5-pin row (pins numbered 1-5 from right to left)

 

KB ID: DD2127080


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