Campbell Scientific CR200/CR200X-series Dataloggers - Manual (Page 49)

Section 4. Sensor Support
Several features give the CR200(X) the flexibility to measure many sensor
types. Contact a Campbell Scientific applications engineer if assistance is
required to assess sensor compatibility.
4.1 Powering Sensors
Read More! See CR200(X) Power Supply (p. 53).
The CR200(X) is a convenient router of power for sensors and peripherals
requiring a 2.5, 5 or 12 VDC source. It has one program-controlled switched 12
Volt terminal (SW Battery), and two switched voltage excitation terminals
(VX1, VX2). These terminals limit current internally for protection against
accidental short circuits. Sensors can be powered continuously by connecting to
the Battery + terminal, which is the same as connecting sensors directly to the
external battery.
Voltage on the Battery + and SW Battery terminals will changed with the DC
supply used to power the CR200(X). The switched voltage excitation terminals
are typically used to supply a brief excitation for a bridge measurement with the
ExDelSE () instruction, but can also be programmed to provide a continuous 2.5
V or 5 V using the Excite () instruction, which is enough to power many
sensors. Switched Unregulated (Nominal 12 Volt) (p. 38) shows the current
limits of SW Battery. Greatly reduced output voltages associated with SW
Battery, VX1, and VX2 due to current limit may occur if the current limits
given in the table in TABLE. Current Sourcing Limits p. 38 are exceeded.
4.1.1 Switched Precision
Voltage (0, 2500, 5000 mV)
Two switched analog output (excitation) terminals, VX1 and VX2, operate
under program control. Check the accuracy specification of these channels in
Specifications (p. 35) to understand their limitations. Specifications are only
applicable for loads not exceeding ±25 mA for 2.5 V excitation, or 10 mA for 5
V excitation. CRBASIC instructions that control excitation channels include:
• ExDelSE ()
• ExciteV ()
4.1.2 Continuous Unregulated (Nominal 12 Volt)
Voltage on the Battery + terminal will change with the CR200(X) external
battery voltage.
37