User's Manual

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 StingRay modem for RS-422 operation, use the ATIO 4
command. You must order the RS-422 option for this to work, and only
StingRay modems with Revision E or higher hardware will work in RS-422
mode. The StingRay’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
StingRay 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.
StingRay 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 StingRay 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 StingRay is disabled, as well as certain current-
consuming hardware circuits. The ability of the StingRay to go into LPM is
set with a configuration bit, using the ATRP 1 command. ATRP 1 configures
the StingRay to monitor the DTR input line, and enter the LPM mode
whenever DTR is negated. If the DTR signal is asserted, the StingRay
modem will operate normally.
The ATRP 2 command forces the StingRay modem into the low-power mode.
IN the Low Power mode, the StingRay’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 StingRay modem into the normal-
operating mode with the receiver and transmitter operational.