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| Table | ||
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Pin | Signal |
| Signal Name and Description | |
Number | Mnemonic | |||
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1 |
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| CHASSIS GROUND. Not always used. See section Proper | |
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| Grounding. | |
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2 | TxD |
| TRANSMIT DATA. Data to be transmitted; input to the modem | |
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| from the terminal. | |
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3 | RxD |
| RECEIVE DATA. Data which is demodulated from the receive | |
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| line; output from the modem to the terminal. | |
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4 | RTS |
| REQUEST TO SEND. Input to the modem from the terminal | |
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| when required to transmit a message. With RTS off, the modem | |
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| carrier remains off. When RTS is turned on, the modem | |
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| immediately turns on the carrier. | |
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5 | CTS |
| CLEAR TO SEND. Output from the modem to the terminal to | |
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| indicate that message transmission can begin. When a modem is | |
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| used, CTS follows the | |
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| delay. | |
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6 | DSR |
| DATA SET READY. Output from the modem to the terminal to | |
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| indicate that the modem is ready to transmit data. | |
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7 |
| SIGNAL GROUND. Common return line for all signals at the | ||
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| modem interface. | |
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8 | DCD |
| DATA CARRIER DETECT. Output from the modem to the | |
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| terminal to indicate that a valid carrier is being received. | |
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| Not used. | ||
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15 | TxC |
| TRANSMIT CLOCK (DCE). Output from the modem to the | |
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| terminal; clocks data from the terminal to the modem. | |
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16 |
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| Not used. | |
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17 | RxC |
| RECEIVE CLOCK. Output from the modem to the terminal; | |
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| clocks data from the modem to the terminal. | |
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18, 19 |
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| Not used. | |
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20 | DTR |
| DATA TERMINAL READY. Input to the modem from the | |
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| terminal; indicates that the terminal is ready to send or receive | |
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| data. | |
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21 |
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| Not used. | |
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