SIM508 EVB User Guide
SIMCOM
3.5 RS232 interface
3.5.1 GSM part:
Figure 9: GSM part serial ports
Serial Port 1
Pin
Signal
I/O
Description
1 DCD O
Data carrier detection
2 TXD O
Transmit data
3 RXD I
Receive data
4 DTR I
Data Terminal Ready
5 GND
GND
7 RTS I
Request to Send
8 CTS O
Clear to Send
9 RI O
Ring Indicator
Serial Port 2
Pin
Signal
I/O
Description
2 DEBUG_TX O
Transmit data
3 DEBUG_RX I
Receive data
5 GND
GND
SIM508-EVB_UGD_V1.01 Page 13 of 25
