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Chapter 3
Table 3-4
defines the pins and corresponding signals for serial ports 1 and 2 headers (J3 and J4), which each
consist of 10 pins, 2 rows, odd/even sequence (1, 2), and 0.079" (2mm) pitch.
Table 3-4. Serial Ports 1 & 2 Interface Pin Signal Descriptions (J3 and J4)
Pin # Signal
1
DCD*
2
DSR*
3
RXD
Rx Data –
4
RTS*
Tx Data +
5
TXD
Tx Data –
6
CTS*
Rx Data +
7
DTR*
8
RI*
9
GND
10
Key/NC
Note: The shaded table cell denotes power or ground. The * symbol indicates the signal is Active Low.
24
DB9 # Description
1
Data Carrier Detect – 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 DTR as part of the
DTR/DSR handshake.
6
Data Set Ready – Indicates external serial device is powered, initialized,
and ready. Used as hardware handshake with DTR for overall readiness.
2
Receive Data – Serial port receive data input is typically held at a logic 1
(mark) when no data is being transmitted, and is held "Off" for a brief
interval after an "On" to "Off" transition on the RTS line to allow the
transmission to complete.
Serial Port 1 or 2 – If in RS-485 mode, this pin is Rx Data Negative.
7
Request To Send – Indicates serial port is ready to transmit data. Used as
hardware handshake with CTS for low level flow control.
Serial Port 1 or 2 – If in RS-485 mode, this pin is Tx Data Positive.
3
Transmit Data – Serial port transmit data output is typically held to a
logic 1 when no data is being sent. Typically, a logic 0 (On) must be
present on RTS, CTS, DSR, and DTR before data can be transmitted on
this line.
Serial Port 1 or 2 – If in RS-485 mode, this pin is Tx Data Negative.
8
Clear To Send – Indicates external serial device is ready to receive data.
Used as hardware handshake with RTS for low level flow control.
Serial Port 1 or 2 – If in RS-485 mode, this pin is Rx Data Positive.
4
Data Terminal Ready – Indicates serial port is powered, initialized, and
ready. Used as hardware handshake with DSR for overall readiness.
9
Ring Indicator – Indicates external serial device is detecting a ring
condition. Used by software to initiate operations to answer and open the
communications channel.
5
Ground
NC
Key Pin/Not connected
Reference Manual
Hardware
CoreModule 745
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