Specifications

Chapter 3 Hardware
38 Reference Manual ReadyBoard 800
Serial B Interface (J11A/B)
Table 3-10. Serial B Interface Pin/Signal Descriptions (J11A/B)
Pin # Pin #
DB9
Signal Description
A1 1
(COM3)
DCD3* Data Carrier Detect 3 – Indicates external serial device is detecting a carrier
signal (i.e., a communication channel is currently open). In direct connect
environments, this input is driven by DTR3 as part of the DTR/DSR
handshake.
A2 6 DSR3* Data Set Ready 3 – Indicates external serial device is powered, initialized,
and ready. Used as hardware handshake with DTR3 for overall readiness.
A3 2 RXD3
RX3-
Receive Data 3 – Serial port 3 receive data in.
RX3 Negative – If in RS-485 or RS-422 mode, this pin is Receive Data 3 -.
A4 7 RTS3*
TX3+
Request To Send 3 – Indicates serial port is ready to transmit data. Used as
hardware handshake with CTS3 for low level flow control.
TX3 Positive – If in RS-485 or RS-422 mode, this pin is Transmit Data 3 +.
A5 3 TXD3
TX3-
Transmit Data 3 – Serial port 3 transmit data out.
TX3 Negative – If in RS-485 or RS-422 mode, this pin is Transmit Data 3 -.
A6 8 CTS3*
RX3+
Clear To Send 3 – Indicates external serial device is ready to receive data.
Used as hardware handshake with RTS3 for low level flow control.
RX3 Positive – If in RS-485 or RS-422 mode, this pin is Receive Data 3 +.
A7 4 DTR3* Data Terminal Ready 3 – Indicates serial port is powered, initialized, and
ready. Used as hardware handshake with DSR3 for overall readiness to
communicate.
A8 9 RI3* Ring Indicator 3 – Indicates external serial device is detecting a ring
condition. Software initiates operation to answer and open the
communications channel.
A9 5 GND Ground
A10 NC NC Not connected/Key
B11 1
(COM4)
DCD4* Data Carrier Detect 4 – Indicates external serial device is detecting a carrier
signal (i.e., a communication channel is currently open). In direct connect
environments, this input is driven by DTR4 as part of the DTR/DSR
handshake.
B12 6 DSR4* Data Set Ready 4 – Indicates external serial device is powered, initialized,
and ready. Used as hardware handshake with DTR4 for overall readiness.
B13 2 RXD4
RX4-
Receive Data 4 – Serial port 4 receive data in.
RX4 Negative – If in RS-485 or RS-422 mode, this pin is Receive Data 4 -.
B14 7 RTS4*
TX4+
Request To Send 4 – Indicates serial port is ready to transmit data. Used as
hardware handshake with CTS4 for low level flow control.
TX4 Positive – If in RS-485 or RS-422 mode, this pin is Transmit Data 4 +.
B15 3 TXD4
TX4-
Transmit Data 4 – Serial port transmit data out.
TX4 Negative – If in RS-485 or RS-422 mode, this pin is Transmit Data 4 -.
B16 8 CTS4*
RX4+
Clear To Send 4 – Indicates external serial device is ready to receive data.
Used as hardware handshake with RTS4 for low level flow control.
RX4 Positive – If in RS-485 or RS-422 mode, this pin is Receive Data 4 +.