User's Manual

Company Confidential 16 Raveon Technologies
7
Out +
out
TX out +
3.3,0V.
8
In -
in
RX input -
9
Vin
In/Out
DC Power
DC Power in or out if unit is powered using DC in
jack.
Configuring for RS-422
To configure the M7-UC modem for RS-422 operation, use the ATIO 4
command. You must order the RS-422 option for this to work, and only M7-
UC modems with Revision E or higher hardware will work in RS-422 mode.
The M7-UC’s hardware is identical to the RS-485 version, with the exception
of two internal loop-back resistors.
Raveon’s RS-422 I/O circuit uses 3.3V logic to drive the lines, and the RS422
pins are ESD protected to ±15kV and 7kV human body model.
RS-422 installations typically have a termination resistor across the In and the
Out lines. A value of 150 ohms should work in most applications.
Bias and Termination Resistors
M7-UC RS-422 receivers have built-in bias resistors, offering the network a
true “1/8 unit load”. In most allocations, these internal bias resistors are
sufficient, and an external bias resistor is not required.
Serial out data comes out pins 3 and 7. Serial input data comes in via pins 4
and 8. Connect pin 5 to earth ground.
M7-UC RS-422 receivers have built-in bias resistors, offering the network a
true “1/8 unit load”. In most allocations, these internal bias resistors are
sufficient, and an external bias resistor is not required.
4.5 Low Power Mode (LPM)
The M7-UC modem, has the ability to be put into a low power mode (LPM).
In LPM the modem draws much less current from the DC input. In LPM, the
internal radio in the M7-UC is disabled, as well as certain current-consuming
hardware circuits. The ability of the M7-UC to go into LPM is set with a
configuration bit, using the ATRP 1 command. ATRP 1 configures the M7-UC
to monitor the DTR input line, and enter the LPM mode whenever DTR is
negated. If the DTR signal is asserted, the M7-UC modem will operate
normally.
The ATRP 2 command forces the M7-UC modem into the low-power mode.
IN the Low Power mode, the M7-UC’s radio circuits are off, but it will still
respond to serial commands and it will still transmit characters over the air,
albeit with some latency as it has to power-up the radio each time it wishes to
transmit.
The ATRP 0 command returns the M7-UC modem into the normal-operating
mode with the receiver and transmitter operational.