Check your device's documentation to see if it requires handshaking, or if it requires any special configuration.Communication plays an important role in distributed applications. If you have determined that your PC's RS-232 port is working correctly, then you need to check your cabling and need to make sure that your device is configured for the same baud rate, parity and stop-bits as your computer's serial port.
This test will only verify that your computer and software is working properly. If you see nothing, with or without the wire connected, then, you may have a bad port, or you may be on the wrong port. If you are not sure if you have "echo-on", then start typing, and then remove the wire from the port, and type again, and you should see the difference. For example, if you type HELLO, you will see HHEELLOO on your screen. If you have your software configured to "echo" the characters, then, you will see each character twice. Anything that you type, should appear on your monitor. Start to type any characters on your keyboard. Baud rate does not matter for this test, since the port will transmit and receive at the same rate. Disable any handshaking, such as RTS/CTS or X-ON/X-OFF. Set up the software to communicate to the correct port number, such as COM1 or COM2.
Run any terminal-emulation program, such as Hyperterminal (included with Windows 95) or Terminal (included with Windows 3.1). Then, slide that coil around the pins of the serial port. If you find it difficult to connect to the pins, you may try to wrap a thin copper wire around one end of an un-wrapped paper clip, creating a small coil. If you are using something other than an IBM or compatible PC, then locate TRANSMIT and connect it to RECEIVE. By shorting these to pins directly together, you are connecting the TRANSMIT line to the RECEIVE line. Connect WireĬonnect a piece of wire from pin 2 to pin 3. A 25-pin port TRANSMITS on pin 2 and RECEIVES on pin 3, and a 9-pin port is exactly the opposite, but for this test, it doesn't matter, since all we want to do is to connect the TRANSMIT line to the RECEIVE line.
Locate pins 2 and 3Ī magnifying glass may be required to read the numbers on the inside base of the connector. If necessary, consult your computer's manual, or contact their technical support department. If you have 2 serial ports, identify if it is COM1 or COM2. Remember, a PC's RS-232 port can be 9-pin or 25-pin, but will always be a male connector (containing pins, not sockets). It is, however, similar for other computers) Identify your serial port (these instructions are for an IBM or compatible.
To perform a "Loop-Back" test, follow these simple steps. A printer port is always a 25-pin female connector.
One important thing to remember is that an RS-232 port on an IBM or compatible PC is always a male connector, and may be either 9 or 25-pin. It is a common mistake to connect a serial device to the printer port, since many believe this to be a 25-pin RS-232 port. There is one very simple test that will help simplify the task of troubleshooting your RS-232 system, which is sometimes called the "Loop-Back" test.īasically, this test will verify that your PC's serial port is working properly, and that the RS-232 software that you are using is operating correctly, and that you are connected to the proper port. Among them are correct baud rate setting for the device, proper software configuration and proper cabling. There are many factors involved in communicating with an RS-232 device from a PC.