RoboteQ AX500 manual Using the Analog Inputs to Monitor External Voltages

Connecting Sensors and Actuators to Input/Outputs

	100
	50
Input Reading	0
Analog	-50
	-100
	-150
	-20	-10	0	10	20	30	40	50	60	70	80	90	100	110

Temperature in Degrees C

FIGURE 31. Signed binary reading by controller vs. NTC temperature

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.

To Battery +Terminal

47kOhm

4.7kOhm

+5V 14

Ana 1: 11

Ana 2: 10

Ana 3: 12

Ana 4: 8

Ground 5

Internal Resistors and Converter

47kOhm

A/D 10kOhm

47kOhm

FIGURE 32. Battery voltage monitoring circuit

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.

58 AX500 Motor Controller User’s Manual Version 1.9b. June 1, 2007