41110590
Rev 6.1
January 28, 2019
21
Product Technical Specification and
User Guide
Interfaces/Peripherals
2.2.1.2.
Serial Link (RS232)
The modem’s serial link, RS232, performs the voltage level adaptation (V24/CMOS) between the
internal Plug & Play (DCE) and external applications (DTE).
The RS232 interface is internally protected against electrostatic surges on its lines by ESD protection.
The RS232 interface has the following filtering guarantees:
•
EMI/RFI protection on both the input and the output
•
Signal smoothing
Signals available on the RS232 serial link are as follows:
•
TX data (RS232-TXD)
•
RX data (RS232-RXD)
•
Request To Send (RS232-RTS)
•
Clear To Send (RS232-CTS)
•
Data Terminal Ready (RS232-DTR)
Modem
(DCE)
DTE
RS232-TXD
GND
RS232-RXD
RS232-RTS
RS232-CTS
RS232-DTR
7
3
8
4
2
TX
RX
RTS
CTS
DTR
Figure 7.
RS232 Serial Link Signals
2.2.1.2.1.
Pin Description
Table 12.
Serial Link Pin Description from the Micro-Fit Connector (CN201)
Pin #
Signal*
I/O**
I/O Type
Reset State
Description
2
RS232-DTR
I
RS-232
Z
Data Terminal Ready
3
RS232-RXD
O
RS-232
1
Receive Serial Data
4
RS232-CTS
O
RS-232
Z
Clear To Send
5
-
-
-
-
Reserved
6
GND
-
GND
Ground
7
RS232-TXD
I
RS-232
Z
Transmit Serial Data
8
RS232- RTS
I
RS-232
Z
Request To Send
*
According to PC (DTE) view.
**
According to modem (DCE) view, from which the direction of the signal is defined.
Note:
The RS232-DTR signal must be managed following the V24 protocol signaling if the Sleep Mode
and Serial Port Shutdown feature are to be used.
