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Section 7b: Identify 202, FSK and RS-422/485 Pinouts with a Butt Set

If you're working with a 202, FSK or RS-422/285 connection, you can use a butt set to identify transmit pins.

1. Connect your butt set to the pin you want to identify.
2. If it's a transmit pin, you'll hear a series of tones in the earpiece.
3. For more information on testing ports with a butt set, see Section 5, "How to Test RS-422 and RS-485 Connections with a Butt Set."

Section 7c: Identify Serial Device Pinouts with a PC

If you're having problems connecting to a serial device, you can use a PC HyperTerminal connection to identify its pinouts.

1. Connect the COM port of your PC to the serial device's port and try establishing a HyperTerminal connection.
2. If you can connect via HyperTerminal, you know the device can connect to a standard PC COM port.

3. Since all PC COM ports have the same standard pinout, you have a reference for identifying the pinout of the serial device's pinout. (See Figure 1 for a standard COM port pinout.)
4. Note: Your connection problems may also be caused by an incorrect baud rate. If you can successfully connect via HyperTerminal, check your PC's baud rate and apply it to all equipment that connects to this device.
5. Note: Your serial device may require handshaking signals. If you can successfully connect via Hyperterminal, check to make sure that all equipment that connects to your serial device supports handshaking.
6. If you can't connect via HyperTerminal, the serial device's port may be broken.

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