Campbell Scientific CR200/CR200X-series Dataloggers - Manual (Page 39)

Section 3. Overview
3.1.3.2 Voltage Outputs
Read More! See Control Output (p. 49).
• Switched Analog Output (Excitation): two channels (VX1/VX2) for
precise voltage excitation ranging from +2500 mV or +5000 mV. These
channels are regularly used with resistive bridge measurements. Each
channel will source up to 25 mA.
• Digital I/O: 2 channels (C1 - C2) configurable for on / off and pulse output
duration.
• Switched 12 Volts (SW Battery): (switch on / off ) primary voltage under
program control for control of external devices requiring 12V DC, such as
humidity sensors. SW Battery can source up to 900 mA. See TABLE.
Current Sourcing Limits p. 38.
• CR200(X) used as a PLC (programmable logic controller): Utilizing
peripheral relays and analog output devices, the CR200(X) can manage
binary and variable control devices through the following output channels:
• Digital I/O: 2 channels (C1/C2) configurable for pulse output duration.
• Switched 12 Volts (SW Battery): (switches on/off) primary voltage
under program control for control of external devices requiring 12V
DC, such as humidity sensors. SW Battery can source up to 900 mA.
See TABLE. Current Sourcing Limits p. 38.
3.1.3.3 Grounding Terminals
Read More! See Grounding (p. 55).
Proper grounding will lend stability and protection to a data acquisition system.
It is the easiest and least expensive insurance against data loss-and the most
neglected. The following terminals are provided for connection of sensor and
datalogger grounding:
• Signal Grounds: 6 ground terminals ( ) used as reference for single-ended
analog inputs, pulse inputs, excitation returns, and as a ground for sensor
shield wires. Signal returns for pulse inputs should use terminals located
next to pulse inputs.
• Power Grounds: 6 terminals (G) used as returns for 5V, SW Battery, 12V,
and C1-C2 outputs. Use of G grounds for these outputs minimizes
potentially large current flow through the analog voltage measurement
section of the wiring panel, which can cause single-ended voltage
measurement errors.
• Ground Lug: 1 terminal ( ), the large ground lug is used to connect a
heavy gage wire to earth ground. A good earth connection is necessary to
secure the ground potential of the datalogger and shunt transients away
from electronics. Minimum 14 AWG wire is recommended.
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