Specifications

Section 4. Sensor Support

4-3

within the ±5000 mV common-mode input range of the amplifier. The

amplifier cannot properly reject common-mode signals that fall outside of the

±5000 mV common-mode input range. See Section 16.2 for more information

on common-mode range.

Two sets of numbers are assigned to analog channels. For

differential measurements, analog channels are numbered 1 - 8.

Each differential channel as two inputs: high (H) and low (L).

For single-ended measurement, analog channels are numbered

1-16.

Sustained voltages in excess of ±16 V input to the analog

channels will damage CR1000 circuitry.

4.2.1 Measurement Sequence

The CR1000 measures analog voltage by integrating the input signal for a fixed

duration and then holding the integrated value during the successive

approximation analog-to-digital (A/D) conversion. The CR1000 can make and

store measurements from up to 8 differential or 13 single-ended channels at the

minimum scan rate of 10 ms (100 Hz) using the fastest available voltage

measurements. The maximum conversion rate is 2700 per second for

measurements made on a single channel.

The timing of CR1000 measurements is precisely controlled. The

measurement schedule is determined at compile time and loaded into memory.

This schedule sets interrupts that drive the measurement task.

Using two different voltage measurement instructions with the same voltage

range takes the same measurement time as using one instruction with two

repetitions.

Historical Lesson: This is not the case with legacy CR10X, 21X, CR23X, and

CR7(X) dataloggers. Using multiple measurement “reps” in these dataloggers

reduced overall measurement time.

Several parameters in CRBASIC voltage measurement instructions VoltDiff()

and VoltSE() vary the sequence and timing of measurements. TABLE 4.2-1

lists th

ese parameters.

TABLE 4.2-1. CRBASIC Parameters Varying Measurement Sequence

and Timing

CRBASIC Parameter Description

MeasOfs Correct ground offset on single-ended measurements.

RevDiff Reverse high and low differential inputs.

SettlingTime Sensor input settling time.

Integ Duration of input signal integration.

RevEx Reverse polarity of excitation voltage.

NOTE