RoboteQ Dual Channel Digital Motor Controller AX2550 - Manual (Page 62)

Connecting Sensors and Actuators to Input/Outputs
62 AX1500 Motor Controller User’s Manual Version 1.9b. June 1, 2007
To read the temperature, use the ?p command to have the controller return the A/D con-
verter’s value. The value is a signed 8-bit hexadecimal value. Use the chart data to convert
the raw reading into a temperature value.
Using the Analog Inputs to Monitor External Voltages
The analog inputs may also be used to monitor the battery level or any other DC voltage. In
this mode, the controller does not use the voltage information but merely makes it avail-
able to the host microcomputer via the RS232 port. The recommended schematic is
shown in Figure 32.
Using these resistor values, it is possible to measure a voltage ranging from -5V to +60V
with a 0.25V resolution. The formula for converting the A/D reading into a voltage value is
as follows.
-150
-100
-50
0
50
100
-20 -10
0
10 20 30 40 50 60 70 80 90
100 110
Temperature in Degrees C
Analog Input Reading
FIGURE 31. Signed binary reading by controller vs. NTC temperature
47kOhm
10kOhm
47kOhm
47kOhm
4.7kOhm
Internal Resistors
and Converter
To Battery
+ Terminal
+5V 14
Ground 5
A/D
Ana 1: 11
Ana 2: 10
Ana 3: 12
Ana 4: 8
FIGURE 32. Battery voltage monitoring circuit