Serial Com1 Port (Cn21); Table 15: Pin Assignment Serial Com1 Port Cn21; Table 16: Signal Description; Figure 11: Serial Com1 Port Cn21 - Kontron ATX-KBL-S User Manual

6.6. Serial COM1 Port (CN21)

The external I/O connector panel supports one DB-9 RS-232/422/485 COM male port.

Figure 11: Serial COM1 Port CN21

Table 15: Pin Assignment Serial COM1 Port CN21

Pin RS232 Signal
B1 DCD
B2 RXD
B3 TXD
B4 DTR
B5 GND
B6 DSR
B7
RTS
B8 CTS
B9 RI*
*: Pin configuration can be selected by Jumper JP15.
RS232 / 422 / 485 can be selected in BIOS setup.

Table 16: 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.
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RS422 Signal Half Duplex
RS485 Signal
TX- DATA-
TX+ DATA+
RX+ N/A
RX- N/A
GND GND
N/A N/A
N/A N/A
N/A N/A
N/A N/A
Full Duplex Note
RS485 Signal
TX-
RX+
TX+
RX-
GND
N/A
N/A
N/A
N/A
ATX-KBL-S - User Guide, Rev. 1.1
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