mITX-SSH-S - User Guide, Rev. 1.0
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7.10.
Serial COM1 & COM2 Ports (CN18 & CN19)
Figure 23: Serial COM CN18, CN19
Table 32: Pin Assignment CN18, CN19
Pin
RS232 Signal
RS422 Signal
Half Duplex
RS485 Signal
Full Duplex
RS485 Signal
Note
1
DCD
TX-
DATA-
TX-
2
DSR
N/A
N/A
N/A
3
RXD
TX+
DATA+
TX+
4
RTS
N/A
N/A
N/A
5
TXD
RX+
N/A
RX+
6
CTS
N/A
N/A
N/A
7
DTR
RX-
N/A
RX-
8
RI
N/A
N/A
N/A
9
GND
GND
GND
GND
10
+5V
+5V
+5V
+5V
The COM ports need to install an OS patch from ITE. The patch is only available for
Windows and is not available Linux.
Table 33: Signal Description
Signal
Description
TXD
Transmitted Data, sends data to the communications link. The signal is set to the marking state (-12
V) on hardware reset when the transmitter is empty or when loop mode operation is initiated.
RXD
Received Data, receives data from the communications link.
DTR
Data Terminal Ready, indicates to the modem etc. that the on-board UART is ready to establish
communication link.
DSR
Data Set Ready, indicates that the modem etc. is ready to establish a communications link.
RTS
Request To Send, indicates to the modem etc. that the on-board UART is ready to exchange data.
CTS
Clear To Send, indicates that the modem or data set is ready to exchange data.
DCD
Data Carrier Detect, indicates that the modem or data set has detected the data carrier.
RI
Ring Indicator, indicates that the modem has received a ringing signal from the telephone line.
TX+/-
Transmitted Data differential pair sends data to the communications link.
