Section 4. Sensor Support
38
4.1.3
Switched Unregulated (Nominal 12 Volt)
Voltage on the SW Battery terminal will change with CR200(X) supply voltage.
The CRBASIC instruction SWBatt () controls the SW Battery terminal.
Table 4.
Current Sourcing Limits
Terminal
Limit
VX1, VX2
25 mA @ 2.5V
10 mA @ 5V
SW Battery
< 900 mA @ 20°C
< 729 mA @ 40°C
< 630 mA @ 50°C
< 567 mA @ 60°C
< 400 mA @ 85°C
4.2 Voltage Measurement
4.2.1
Measurement Sequence
The first step in a voltage measurement is a calibration to measure the ground
offset. The calibration is performed once for each voltage measurement. The
CR200(X) measures analog voltages with a sample and hold analog to digital
(A/D) conversion. The A/D conversion is made with a 12-bit successive
approximation technique which resolves the signal voltage to one part in 4096
of the full scale 2.5 V range, which is 0.6 millivolts.
To reduce noise, 10 measurements are rapidly made and averaged to form the
result returned. The measurements that go into the average each take about 26
microseconds.
4.2.2
Measurement Accuracy
CR200(X) analog measurement error is calculated as
Error = Gain Error (%) + Offset Error
Gain error is expressed as ±% and is a function of input voltage and CR200(X)
temperature. It is minimized by factory calibration and increases with
component temperature and aging. Between -40°C and +50°C, gain error is
typically ±0.25% of the reading with a 1.2 millivolt offset. Worst case over that
same temperature range is ±1% of the reading with a 2.4 millivolt offset.
FIGURE. Voltage Measurement Accuracy (-40° to +50°C)
p. 40 illustrates that
as magnitude of input voltage decreases, measurement error decreases.
Summary of Contents for CR200
Page 32: ...Section 2 Quickstart Tutorial 22 ...
Page 45: ...Section 3 Overview 35 3 3 Specifications ...
Page 46: ...Section 3 Overview 36 ...
Page 58: ...Section 4 Sensor Support 48 ...
Page 62: ...Section 5 Measurement and Control Peripherals 52 ...
Page 78: ...Section 8 CR200 X Configuration 68 ...
Page 102: ...Section 9 Programming 92 ...
Page 138: ...Section 11 Programming Resource Library 128 ...
Page 156: ...Section 16 Support Software 146 ...
Page 160: ...Section 17 Care and Maintenance 150 ...
Page 167: ...Section 18 Troubleshooting 157 18 3 3 2 Charging Circuit Test Solar Panel ...
Page 168: ...Section 18 Troubleshooting 158 18 3 3 3 Charging Circuit Test Transformer ...
Page 169: ...Section 18 Troubleshooting 159 18 3 3 4 Adjusting Charging Circuit Voltage ...
Page 170: ...Section 18 Troubleshooting 160 ...
Page 184: ...Appendix A Glossary 14 ...
Page 190: ...Appendix B Status Table and Settings 20 ...
Page 192: ...Appendix C Serial Port Pin Outs 22 ...
Page 211: ......