Siemens TC35i - Manual (Page 21)

TC35i Terminal Hardware Interface Description
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TC35i_T_HD_v01.05 Page 21/37 10.07.2003
Table 5: 9-pole D-Sub (female) RS-232
Pin no. Signal name I/O Function
1 /DCD O Data Carrier Detected
2 /RXD O Receive Data
3 /TXD I Transmit Data
4 /DTR I Data Terminal Ready
Attention: The ignition of TC35i Terminal is activated via a
rising edge of high potential (+5 ... +15 V)
5 GND - Ground
6 /DSR O Data Set Ready
7 /RTS I Request To Send
8 /CTS O Clear To Send
9 /RI O Ring Indication
The current of all signals is limited by serial resistors:
Outputs: 470
Ohm
Inputs: 1kOhm
TC35i Terminal is designed for use as a DCE. Based on the conventions for DCE-DTE
connections it communicates with the customer application (DTE) using the following
signals:
· Port TxD @ application sends data to TXD of TC35i Terminal
· Port RxD @ application receives data from RXD of TC35i Terminal
The RS-232 interface is implemented as a serial asynchronous transmitter and receiver
conforming to ITU-T V.24 Interchange Circuits DCE. It is configured for 8 data bits, no parity
and 1 stop bit, and can be operated at bit rates from 300bps to 115kbps. Autobauding
supports bit rates from 4.8kbps to 115kbps. Hardware handshake using the /RTS and /CTS
signals and XON/XOFF software flow control are supported.
In addition, the modem control signals /DTR
*) , /DSR, /DCD and /RING are available. The
modem control signal RING (Ring Indication) can be used to indicate, to the cellular device
application, that a call or Unsolicited Result Code (URC) is received. There are different
modes of operation, which can be set with AT commands.
*) The /DTR signal will only be polled once per second from the internal firmware
of TC35i.