User Manual

Serial interface specification: Detailed pin description
Integrator’s Guide – RIM 801D OEM Radio Modem
20
RX
Receive is an output from the radio unit to the host terminal’s Receive input.
This is a TTL/CMOS compatible output that is short-circuit protected. This
line can be connected directly to the input of almost any asynchronous
communications IC.
This line has an impedance of 1 kΩ and will be low when the radio unit is
off. The idle (no data) state of this line is high.
TX
Transmit is an asynchronous serial input to the radio unit, and can be
connected directly to the output of almost any asynchronous
communications IC. This line must be driven by a source with an impedance
of 20 kΩ or lower for operation at high baud rates.
This line is held low through a 20 kΩ resistor when the radio is off. The idle
(no data) state of this line is high.
DTR
Data Terminal Ready is an input to the radio unit and is used to signal that
the Host terminal is ready. When the radio is on, asserting this line low will
cause DSR to also go low, and will allow communication to take place.
Asserting this line high will turn communications off, and will cause DSR to
go high.
DTR should be driven low when the radio is off. Driving DTR high when
the radio is off can cause improper operation, may cause DSR to change
state to an indeterminate value, and will consume unnecessary power.
SG
Signal Ground should be tied to the system ground of the host unit. The
radio must also be grounded with the main power cable to assure proper
operation .