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Modem Cable
In order to operate correctly, your modem cable must support the following signals:
DB25 Pin Signal
2 Transmit Data (TxD)
3 Receive Data (RxD)
4 Request to Send (RTS)
5 Clear to Send (CTS)
6 Data Set Ready (DSR)
7 Signal Ground
8 Data Carrier Detect (DCD)
15 Transmit Clock (TxC)†
17 Receive Clock (RxC)†
20 Data Terminal Ready (DTR)
22 Ring Indicator (RI)
24 External Clock (XCLK)†
† - Not required for asynchronous operation
Synchronous Character Encoding
Your modem supports both NRZ and NRZI character encoding when operating in synchronous
mode. The #N command is used to select the character encoding technique suitable for use with
the computer to which your modem is connected.
Refer to the chapter titled ‘Command Descriptions’ for details of the #N command.
Asynchronous Notes
The Backspace character may be used to edit V.25bis commands in asynchronous mode. No
other editing characters are supported by the modem.
All control characters, other than Carriage Return and Backspace, are ignored by your modem.
Your modem will echo Carriage Return characters only, even if your computer issues Carriage
Returns and Line Feeds at the end of a command.
BSC Notes
Commands must start with a STX and end with an ETX to be accepted by the modem.
Control characters that do not form part of the frame are treated as a normal characters. This
usually results in the modem issuing an INV indication.