Chapter 3 |
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| Hardware | |
Table | ||||
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| Pin # | Signal | DB9 # | Description |
| 1 | DCD* | 1 | Data Carrier Detect – Indicator to the serial port that external modem is |
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| detecting a carrier signal (i.e., a communication channel is currently |
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| open). In direct connect environments, this input will be driven by DTR |
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| as part of the DTR/DSR handshake. |
| 2 | DSR* | 6 | Data Set Ready – Indicator to the serial port that external serial |
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| communications device is powered, initialized, and ready. Used as |
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| hardware handshake with DTR1 for overall readiness to communicate. |
| 3 | RXD | 2 | Receive Data – Serial port receive data input is typically held at a logic |
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| 1 (mark) when no data is being transmitted, and is held “Off” for a brief |
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| interval after an “On” to “Off” transition on the RTS line to allow the |
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| RX Data – |
| transmission to complete. |
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| Serial Port 1 or 2 – If in RS485 mode, this pin is RX Data | |
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| 4 | RTS* | 7 | Request To Send – Indicates serial port is ready to transmit data. Used |
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| Tx Data + |
| as hardware handshake with CTS for low level flow control. |
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| Serial Port 1 or 2 – If in RS485 mode, this pin is TX Data +. | |
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| 5 | TXD | 3 | Transmit Data – Serial port transmit data output is typically held to a |
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| logic 1 when no data is being sent. Typically, a logic 0 (On) must be |
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| present on RTS, CTS, DSR, and DTR before data can be transmitted on |
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| Tx Data – |
| this line. |
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| Serial Port 1 or 2 – If in RS485 mode, this pin is TX Data | |
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| 6 | CTS* | 8 | Clear To Send – Indicator to the serial port that external serial |
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| communication device is ready to receive data. Used as hardware |
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| Rx Data + |
| handshake with RTS for low level flow control. |
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| Serial Port 1 or 2 – If in RS485 mode, this pin is RX Data +. | |
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| 7 | DTR* | 4 | Data Terminal Ready – Indicates serial port is powered, initialized, and |
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| ready. Used as hardware handshake with DSR for overall readiness to |
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| communicate. |
| 8 | RI* | 9 | Ring Indicator – Indicator to serial port that external modem is detecting |
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| a ring condition. Used by software to initiate operations to answer and |
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| open the communications channel. |
| 9 | GND | 5 | Digital Ground |
| 10 | KEY/NC | NC | Key Pin/Not connected |
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Notes: The shaded area denotes power or ground. The signals marked with * indicate active low.
Table
Pin # | Signal | DB9 # | Description |
1 | DCD* | 1 | Data Carrier Detect – Indicator to serial port that external modem is |
|
|
| detecting a carrier signal (i.e., a communication channel is currently |
|
|
| open). In direct connect environments, this input will be driven by DTR |
|
|
| as part of the DTR/DSR handshake. |
2 | DSR* | 6 | Data Set Ready – Indicator to serial port that external serial |
|
|
| communications device is powered, initialized, and ready. Used as |
|
|
| hardware handshake with DTR for overall readiness to communicate. |
3 | RXD | 2 | Receive Data – Serial port receive data input is typically held at a logic |
|
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| 1 (mark) when no data is being transmitted, and is held “Off” for a brief |
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| interval after an “On” to “Off” transition on the RTS line to allow the |
|
|
| transmission to complete. |
34 | Reference Manual | CoreModule 420 |
