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Section 5: How to Test 202, FSK, and RS-422/RS-485 Connections with a Butt Set

1. You can use a butt set to listen for data as well as voice.

   Connect an ordinary butt set to the transmit leads of the problem port. Force an alarm and listen for a series of tones.

What's going on: If you connect a phone handset to a 202, FSK or RS-422/485 line, the digital data signal will make audible sounds in the earpiece. This won't tell you anything about the quality of the data transmission … but it will tell you if there's a signal on the line.

2. Do you hear any data coming from the transmit port?
3. If you don't hear any data, you may have a cabling issue. Double-check the transmit port pinout.
4. If you do hear data on the transmit port, clip your butt set to the transmit leads of the receive port and listen. If the receiver device is receiving information, it should also be transmitting information.
5. Do you hear any data coming from the receive port?
6. If you don't hear any data, double-check the RTU's address.
7. If the address is OK, you may have a cabling issue. Double-check the receive port pinout.
8. If you believe that the pinouts are OK, and data is being transmitted at both ends, but the connection still isn't working correctly, double-check the configuration of both the transmitter and receiver device.

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