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Chapter 3 Hardware
MightyBoard 821 Reference Manual 19
Note: The shaded area denotes power or ground.
Table 3-4. Serial 2 (COM2) Interface Pin/Signal Descriptions (J6)
Pin # Pin #
DB9
Signal Description
1 1 DCD2* Data Carrier Detect 2 – Indicates external serial communications device is
detecting a carrier signal (i.e., a communication channel is currently open).
In direct connect environments, this input will be driven by DTR2 as part
of the DTR2/DSR2 handshake.
2 6 DSR2* Data Set Ready 2 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with DTR2
for overall readiness to communicate.
3 2 RXD2 Receive Data 2 – Serial port 2 receive data in
4 7 RTS2* Request to Send 2 – Indicates Serial port 2 is ready to transmit data. Used
as hardware handshake with CTS2 for low level flow control.
5 3 TXD2 Transmit Data 2 – Serial port 2 transmit data out
6 8 CTS2* Clear to Send 2 – Indicates external serial communications device is ready
to receive data. Used as hardware handshake with RTS2 for low level flow
control.
7 4 DTR2* Data Terminal Ready 2 – Indicates Serial port 2 is powered, initialized, and
ready. Used as hardware handshake with DSR2 for overall readiness to
communicate.
8 9 RI2* Ring Indicator 2 – Indicates external serial communications device is
detecting a ring condition. Used by software to initiate operations to
answer and open the communications channel.
95
GND Ground
10 NC NC Not connected
Table 3-5. Serial 3 and 4 (COM3 and COM4) Interface Pin/Signal Descriptions (J15)
Pin # Pin #
DB9
Signal Description
1 1(COM3) DCD3* Data Carrier Detect 3 – Indicates external serial communications
device is detecting a carrier signal (i.e., a communication channel is
currently open). In direct connect environments, this input will be
driven by DTR3 as part of the DTR3/DSR3 handshake.
2 6 DSR3* Data Set Ready 3 – Indicates external serial communications device is
powered, initialized, and ready. Used as hardware handshake with
DTR3 for overall readiness to communicate.
3 2 RXD3
RX3-
Receive Data 3 – Serial port 3 receive data in
RX3- – If in RS485 or RS422 mode, this pin is Receive Data 3 -.
47RTS3*
TX3+
Request To Send 3 – Indicates Serial port 3 is ready to transmit data.
Used as hardware handshake with CTS3 for low level flow control.
TX3+ – If in RS485 or RS422 mode, this pin is Transmit Data 3 +.
5 3 TXD3
TX3-
Transmit Data 3 – Serial port 3 transmit data out
TX3- – If in RS485 or RS422 mode, this pin is Transmit Data 3 -.