Section 5. Measurement and Control Peripherals
50
Figure 33: Control Port Current Sourcing
5.1.1.2
Switched 12 V Control
The SW Battery port can be set low (0 V) or high (12 V) using the SWBatt ()
instruction. The port is often used to control low power devices such as sensors
that require 12 V during measurement. Current sourcing must be limited to 900
mA or less at 20°C. See
TABLE. Current Sourcing Limits
(p. 38).
A 12V switching circuit, driven by a digital I/O port, is also available from
Campbell Scientific.
Note
The SW Battery supply is unregulated and can supply up to 900 mA at
20°C. See
TABLE. Current Sourcing Limits
(p. 38). A resettable polymeric
fuse protects against over-current. Reset is accomplished by removing the load
or turning off the SW Battery for several seconds.
5.1.1.3
Relays and Relay Drivers
Compatible, inexpensive and reliable single-channel relay drivers for a wide
range of loads are available from various electronic vendors such as Crydom,
Newark, Mouser, etc.
5.1.1.4
Component Built Relays
FIGURE. Relay Driver Circuit with Relay
(p. 51) shows a typical relay driver
circuit in conjunction with a coil driven relay which may be used to switch
external power to some device. In this example, when the control port is set
high, 12 V from the datalogger passes through the relay coil, closing the relay
which completes the power circuit and turns on the fan.
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: ......