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RS232 Serial Loopback Connections
- pinout and connections for an RS232 serial loopback test on both DB9 and DB 25 way connectors..
RS232 tutorial includes:
• RS232 tutorial • EIA & RS232 standards • RS232 Handshaking • RS232 signals and voltage levels • RS232 pinouts • RS232 loopback • RS232 serial data cables
It is sometimes useful to be able to use what is termed an RS232 loopback connector. This form of serial loopback connector can be used to test a serial port and see whether the serial port is working correctly. A serial loopback connector enabling this form of test can be particularly useful in many applications.
RS232 loopback connectors are very easy to make up. Serial loopback connectors can be made very easily either for DB9 or DB25 way connectors.
The loopback plug connects serial inputs to serial outputs so that the port may be tested. There is more than one way to wire up a serial loopback connector. The connections given below form a commonly used configuration. Although it may not be necessary to incorporate all the handshaking connections for all applications, they have nevertheless been incorporated so that the serial loopback connector should work for all situations.
DB9 Serial Loopback Connections
The connections for the serial loopback connector are given below in tabular as well as diagrammatic form.
| Connection 1 | Connection 2 | Connection 3 | |
|---|---|---|---|
| Link 1 | 1 | 6 | 4 |
| Link 2 | 2 | 3 | -- |
| Link 3 | 7 | 8 | -- |
DB25 Serial Loopback Connections
| Connection 1 | Connection 2 | Connection 3 | |
|---|---|---|---|
| Link 1 | 2 | 3 | -- |
| Link 2 | 4 | 5 | -- |
| Link 3 | 6 | 20 | 8 |
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