Instructions

13
2.4 SIM card reader
The HT910 Terminal is fitted with a SIM card reader designed for 3V SIM cards. It is the flip-up type which is
lockable in the horizontal position and is accessed through a removable panel.
2.5 RS232 Serial Port
The modem supports a standard RS232 serial interface (EIA/TIA 574) via its 9 pin Sub-D connector, shown
below. In line with serial communication terminology the HT910 Terminal should be considered as the data
circuit-terminating equipment (DCE) and the external application or computer as the data terminating
equipment (DTE). The maximum baud rate to communicate with the HT910 Terminal is 230,4 kbit/s.
PIN
Signal
Direction
Voltage levels
Description
1
DCD
Output
> + 4V
<- 4 V
Data carrier detect
2
RD
Output
> + 4V
<- 4 V
Received data
3
TD
Input
> + 2,4V
< 0.8 V
Transmitted data
4
DTR
Input
> + 4V
< 0.8 V
Data terminal ready
5
GND
-
0 V
Ground connection
6
DSR
Output
> + 4V
< - 4 V
Data set ready
7
RTS
Input
> + 2,4V
< 0.8 V
Request to send
8
CTS
Output
> + 4V
< - 4 V
Clear to send
9
RI
Output
> + 4V
< - 4 V
Ring indicator
Table 6: Electrical characteristics of the serial port signals
2.5.1 Serial Data
The modem supports the standard data character format of
 Programmable baud rate
 Auto-configuration mode with auto-baud.
2.5.2 Serial Data Signals
Serial Data from Modem (RD)
RD is an output signal that the modem uses to send data to the application.
Serial Data To Modem (TD)
TD is an input signal, used by the application to send data to the modem.