Microwave Data Systems MDS 4310, Installation, Operation & Field Maintenance

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MDS 05-2415A01, Rev. A INSTALLATION 2-7
NOTES
For Table 2-1
1. The radio is configured as DCE (data circuit-terminating equipment), as opposed to
DTE (data terminal equipment).
2. When using an internal modem, other pin functions of the DB-25
INTERFACE
connector, such as PTT, Receive Audio, Transmit Audio and RSSI, are still active
and should normally be left open (unterminated). Connecting these pins to an
external device such as a computer, RTU or PLC that also uses these pins for
auxiliary connections can cause improper operation. The use of an interface cable
that connects only the required pins is recommended.
3. Pins 1-8 are standard RS-232-C lines.
INTERFACE
Connector Pin Functional Descriptions
The following description covers the
INTERFACE
connector pin functions. The pin
descriptions are identical whether or not a modem is installed.
PIN 1: Shield
Connected to ground (negative supply potential) at the radio PC board.
PIN 2: TXD—Transmitted Data Input
without modem
This pin is connected to the data input port of the microcontroller and is used with
an external programming terminal.
with internal modem
As above, this pin is also connected to the data input port (TXD) of the internal
modem and is RS-232 compatible.
PIN 3: RXD—Received Data Output
without modem
This pin is connected to the data output port of the microcontroller and is also
used with an external programming terminal.
with internal modem
As above, this pin also provides an RS-232 compatible output of data received by
modem.
PIN 4: RTS—Request-To-Send Input
with internal modem
An RS-232 compatible input to modem which keys transmitter when RTS is at
logic “high”.
PIN 5: CTS—Clear-To-Send Output
with internal modem
An RS-232 compatible output to external RTU or terminal, which goes “high”
after the pre-programmed CTS delay time has elapsed.