Analog measurement specifications

4 single-ended (SE) or 2 differential (DIFF) terminals individually configurable for voltage, thermocouple, current loop, ratiometric, and period average measurements, using a 24-bit ADC. One channel at a time is measured.

Voltage measurements

Terminals:

  • Differential Configuration: DIFF 1H/1L – 2H/2L
  • Single-Ended Configuration: SE1 – SE4

Input Resistance:

  • 5 GΩ typical (fN1 = 50/60 Hz)
  • 300 MΩ typical (fN1 = 4000 Hz)

Input Voltage Limits: -100 to +2500 mV

Sustained Input Voltage without Damage:

  • SE1-SE2: –6 V, +9 V
  • SE3-SE4: ±17 V

DC Common Mode Rejection:

  • >120 dB with input reversal
  • ≥90 dB without input reversal

Normal Mode Rejection:

  • >71 dB at 50 Hz
  • >74 dB at 60 Hz

Input Current @ 25 °C:

  • ±.08 nA typical (fN1 = 50/60 Hz)
  • ±13 nA typical (fN1 = 4000 Hz)

Filter First Notch Frequency (fN1) Range: 50/60, 400, 4000 Hz (user specified)

Analog Range and Resolution:

  Differential with input reversal Single-ended and
differential without input reversal
Notch frequency
(fN1) (Hz)		 Range1
(mV)		 RMS
(µV)		 Bits2 RMS
(µV)		 Bits2
4000 –100 to +2500
–34 to +34		 23
3.0		 16.8
14.5		 33
4.2		 16.3
14.0
400 –100 to +2500
–34 to +34		 3.8
0.58		 19.4
16.8		 5.4
0.82		 18.9
16.3
50/603 –100 to +2500
–34 to +34		 1.6
0.23		 20.6
18.2		 2.3
0.33		 20.1
17.7

1 Range overhead of ~10% on all ranges guarantees that full-scale values will not cause over range

2 Typical effective resolution (ER) in bits; computed from ratio of full-scale range to RMS resolution.

3 50/60 corresponds to rejection of 50 and 60 Hz ac power mains noise.

Accuracy (does not include sensor or measurement noise):

  • 0 to 40 °C: ±(0.04% of measurement + offset)
  • –40 to 70 °C: ±(0.1% of measurement+ offset)

Voltage Measurement Accuracy Offsets:

  Typical offset (µV RMS)
Range (mV) Differential
with input reversal		 Differential
without input reversal		 Single-ended
–100 to +2500 ±20 ±40 ±60
–34 to +34 ±6 ±14 ±20

Measurement Settling Time: 10 µs to 50 ms; 500 µs default

Multiplexed Measurement Time:

These are not maximum speeds. Multiplexed denotes circuitry inside the data logger that switches signals into the ADC.

Measurement time = (multiplexed measurement time + settling time) • reps +0.8 ms

  Differential
with input reversal		 Single-ended or differential
without input reversal
Example fN11 (Hz) Time2 (ms) Time2 (ms)
4000 2.9 1.4
400 14.6 7.3
50/60 103 51.5

1 Notch frequency (1/integration time).

2 Default settling time of 500 µs used.

See also Voltage measurements.