Null Modem Cable Architecture
The following table shows the required hardware for a serial port connection.
| Requirement | Description |
|---|---|
| Null modem cable | A type of serial cable used for obtaining standard debug messages. |
The following table shows the pin settings for a 9-pin null modem cable.
| Data Terminal Equipment (DTE) | Data Communications Equipment (DCE) | Label |
|---|---|---|
| 1, 6 | 4 | CD, DSR - DTR |
| 2 | 3 | RD - TD |
| 3 | 2 | TD - RD |
| 4 | 1, 6 | DTR - CD, DSR |
| 5 | 5 | Gnd - Gnd |
| 7 | 8 | RTS - CTS |
| 8 | 7 | CTS - RTS |
Note 9 is NC on both ends.
The following table shows the pin settings for a 25-pin null modem cable. RTS and CTS are crossed to support hardware flow.
| DTE | DCE | Label |
|---|---|---|
| 2 | 3 | TD - RD |
| 3 | 2 | RD - TD |
| 4 | 5 | RTS - CTS |
| 5 | 4 | CTS - RTS |
| 6, 8 | 20 | DSR, DCD - DTR |
| 7 | 7 | Gnd - Gnd |
| 20 | 6, 8 | DTR - DSR, DCD |
See Also
CEPC How-to Topics | How to Configure a CEPC to Download an OS Image
Last updated on Wednesday, April 13, 2005
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