Chapter 3 – Electrical Characteristics
Wireless ModemModule MTMMC-G-F1 and MTMMC-G-F2 Developer’s Guide
19
Serial Link
A serial link interface is available complying with V24 protocol signaling but not with V28 (electrical interface) due
to a 2.8 Volts interface. TX, RTS and DTR can be either 5V or 3V.
The signals are Tx data (CT103/TX), Rx data (CT104/RX), Request To Send (CT105/RTS), Clear To Send
(CT106/CTS), Data Terminal Ready (CT108-2/DTR) and Data Set Ready (CT107/DSR).
The set of RS232 signals can be required for GSM DATA services application. The 2 additional signals are Data
Carrier Detect (CT109/DCD) and Ring Indicator (CT125/RI).
Table 3-8: Serial Link Pin Description
Signal
Pin Number
I/O
I/O Type*
Description
CT103 / TX
25
I
CMOS
Transmit serial data
CT104 / RX
28
O
1X
Receive serial data
CT105 / RTS
30
I
CMOS
Ready to send
CT106 / CTS
13
O
1X
Clear to send
CT107 / DSR
27
O
1X
Data set ready
CT108-2 / DTR
29
I
CMOS
Data terminal ready
CT109 / DCD
5
O
CMOS / 2X
Data carrier detect
CT125 / RI
9
O
CMOS / 2X
Ring indicator
* See “Table 3-2: Operating Conditions” in section on the
50-pin Connector Description
.