12
AR2700
User’s Manual
3.1.4
RS422 Serial Communications (Green, Pink, Yellow, Grey)
RS422
: RS422 is normally used for faster speeds and longer distances of
communications. Two wires, usually twisted together, carry each differential (noise-
immune) signal. There are no standard PC connections. A special adapter is required to
connect to a PC using RS422.
Wire
Pin
Function in All Modes
Green
4
RS422 TX+
Pink
5
RS422 RX-
Yellow
6
RS422 TX-
Grey
8
RS422 RX+
Red / Blue
12
Ground
– measurement signal
3.1.5
Analog Output (Grey/Pink, Red/Blue)
The Red/Blue wire is the return signal for the Analog Output. It is connected to ground
inside the sensor and should not be connected to ground outside the sensor.
Inadvertently connecting it to ground may cause a reduction in accuracy of the analog
output. The analog signal for distance is a 4-20 mA current loop. Sensor error signaling
can be configured to output either 3 mA or 21 mA.
In Current Loop mode the Grey / Pink wire delivers a current proportional to the
measured distance. The resolution is characterized by a 16-bit digital-to-analog
converter.
Figure 4 Wiring Diagram for Analog output
The best conversion to voltage is obtained by connecting a 100 ohm load resistor
(<500 ohms, 0.5 Watt minimum) between the Grey/Pink and Red/Blue wires at the
measurement point.
