Measurement Computing USB-2408 Series - Manual (Page 21)

21
Chapter 4
Specifications
All specifications are subject to change without notice.
Typical for 25 °C unless otherwise specified.
All specifications apply to all temperature and voltage input channels unless otherwise specified.
Specifications in italic text are guaranteed by design.
Analog input
Table 1. General analog input specifications
Parameter Conditions Specification
A/D converter type ADS1256, 24-bit Sigma Delta
A/D data rates 3750 S/s, 2000 S/s, 1000 S/s, 500 S/s, 100 S/s, 60 S/s, 50 S/s,
25 S/s, 10 S/s, 5 S/s, 2.5 S/s
Throughput  Single channel: 2.5 S/s to 1102.94 S/s (software-selectable)
 Multiple channels: 0.16 S/s to 551.47 S/s (software-selectable)
See Table 11 and Table 12 for details.
Number of channels 16 single-ended or 8 differential (software-selectable).
Thermocouples require differential mode. For each channel
configured as differential, you essentially lose two single-ended
channels.
Input isolation 500 VDC min between field wiring and USB interface
Channel configurations Temperature sensor input, software-selectable to match sensor
type
Voltage input
Input voltage range Thermocouple mode ±0.078125 V
Voltage mode (Note 1) ±10 V, ±5 V, ±2.5 V, ±1.25 V, ±0.625 V, ±0.3125 V,
±0.15625 V, ±0.078125 V (software-selectable)
Absolute maximum input
voltage CxH-CxL relative to
GND  ±22 V max (power on)
 ±10 V max (power off)
Input impedance  10 MΩ (power on)
 390 Ω (power off)
Input leakage current ±20 nA
Input voltage >±30 V
(power on/off) ±1 µA max
Input capacitance 590 pf
Maximum working
voltage (signal + common
mode) Voltage mode ±10.25 V max
Common mode rejection
ratio (Note 1) Thermocouple mode,
(f
IN
= 60 Hz)
110 dB
Voltage mode,
(f
IN
= 60 Hz, all input
ranges)
90 dB
ADC resolution 24 bits
Crosstalk Adj chan, DIFF mode 100 dB
Input coupling DC
Channel gain queue Up to 64 elements Software-selectable channel and range
Warm-up time 45 minutes min
Open thermocouple detect Software-selectable for each channel.
CJC sensor accuracy 15 °C to 35 °C ±0.5 °C typ
0 °C to 55 °C ±1.0 °C max