CL4424 User’s Manual
2. Interfacing Protocol
The CL4424 is a DCE (Data Communications Equipment). A DCE can be interfaced to a DTE using a straight through serial cable (the serial cable provided with the CL4424 is a straight through cable). Typically, PC’s are defined as a DTE and peripherals are defined as DCE. To interface a DCE with another DCE, or a DTE with another DTE, a null modem (or a Crossover) cable is required. The null modem simply swaps pins to convert a DCE to a DTE and
The CL4424 transceivers support the following interface protocols
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Table 1 – DTE, DCE and Null Modem Signal Definitions
DCE Pin | DCE Signal | DCE | DTE Pin | DTE Signal | DTE | Null Modem | Null Modem |
Number | Name | Direction | Number | Name | Direction | Female DB9 | Male DB9 |
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1 | DCD | O | 1 | DCD | I | 1 | NC |
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2 | TXD | O | 2 | RXD | I | 2 | 3 |
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3 | RXD | I | 3 | TXD | O | 3 | 2 |
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4 | DTR | I | 4 | DTR | O | 4 | 6 |
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5 | GND |
| 5 | GND |
| 5 | 5 |
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6 | DSR | O | 6 | DSR | I | 6 | 4 |
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7 | RTS | I | 7 | RTS | O | 7 | 8 |
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8 | CTS | O | 8 | CTS | I | 8 | 7 |
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9 | RI | O | 9 | RI | I | 9 | NC |
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6/21/2005 | 10 |
