Specifications

Chapter 3 Hardware
34 Reference Manual CoreModule 420
Table 3-12. Serial Ports 1 & 2 Interface Pin/Signal Descriptions (J3, J9)
Pin # Signal DB9 # Description
1DCD* 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.
2 DSR* 6 Data Set Ready – Indicates external serial device is powered, initialized,
and ready. Used as hardware handshake with DTR for overall
readiness.
3RXD
Rx Data –
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.
4RTS*
Tx Data +
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.
5TXD
Tx Data –
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.
6CTS*
Rx Data +
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.
7 DTR* 4 Data Terminal Ready – Indicates serial port is powered, initialized, and
ready. Used as hardware handshake with DSR for overall readiness.
8RI* 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.
9 GND 5 Ground
10 Key/NC NC Key Pin/Not connected
Notes: The shaded area denotes power or ground. The signals marked with * indicate active low.
Table 3-13. Serial Ports 3 & 4 Interface Pin/Signal Descriptions (J13, J14)
Pin # Signal DB9 # Description
1 DCD* 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.
2 DSR* 6 Data Set Ready – Indicates external serial device is powered,
initialized, and ready. Used as hardware handshake with DTR for
overall readiness.
3RXD 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.