User Manual

OSMAC BaseOSMAC Base User Manual
Page 36
10 External Connectors
10.1 External Transceiver
The OSMAC BaseOSMAC Base may utilize an internal transceiver, an external transmitter, or an external transceiver. A 15 pin
D-sub connector is located on the rear of the OSMAC BaseOSMAC Base to facilitate interfacing an external transmitter or
external transceiver to the . The pin-out of this connector is as follows:
External Transceiver I/O Connector Pin Out
Pin Number Function
1 Ground
2 B+ for the radio. Internally jumper selectable between +8V and +12V. 1 Amp maximum
current draw.
3 +8V TX. This pin floats when in the RX mode, and will be pulled to +8V when in the TX
mode. 50 mA maximum current source.
4 +5V for radio. 50 mA maximum current draw.
5 +5VRX. This pin floats in the TX mode, and will have +5V when in the RX mode. 50 mA
maximum current source.
6 TX audio. Approximately 1.7V p-p for full system deviation. 2.5V DC nominal bias on
this signal.
7 PTT out. Open collector output, pulls low to ground when the transmitter’s PA should be
on.
8 Do not use and do not connect to anything.
9 Do not use and do not connect to anything.
10 Do not use and do not connect to anything.
11 TX data out. This is the TTL POCSAG data output in the transmit mode.
12 Receiver signal strength indication input. Positive voltage represents carrier present on
channel.
13 RX audio input. 1.0V p-p for a signal with full system deviation.
14 CTCSS tone encoder output.
15 Do not use and do not connect to anything.
10.2 Serial I/O Ports
The OSMAC BaseOSMAC Base has two RS-232 type serial I/O ports on it. The EIA/TIA RS-232, and the equivalent European
CCITT V.28, are electrical standards that cover the signal levels, drive level, and slew rate of compliant
devices. It is important to note that they do not specify baud rates, data formats, or connector pin-outs. These
are set by industry standards and practices.
Equipment using RS-232 ports is grouped into two categories:
DTE Data Terminal Equipment (computers, mainframes, terminals)
DCE Data Communications Equipment (modems, printers, etc.)
The OSMAC BaseOSMAC Base is wired as a peripheral (DCE) device.