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25
Chapter 5
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 samples per second (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 Hz to 1102.94 Hz, software selectable
Multiple channels: 0.16 Hz to 1102.94 Hz, software selectable
See Table 18 and Table 19 for details.
Number of channels
Up to 32 channels individually software-configurable as single-
ended or differential
Thermocouples require differential mode. For each channel
configured as differential, you essentially lose one single-ended
channel. You can add channels by connecting to an
OMB-AI-EXP32.
Input isolation
500 VDC minimum between field wiring and USB interface
Channel configurations
Temperature sensor input, s/w programmable to match sensor type
Voltage input
Input voltage range
Thermocouple mode
±0.078125 V
Voltage mode (Note 1)
±20 V, ±10 V, ±5 V, ±2.5 V, ±1.25 V, ±0.625 V, ±0.3125 V,
±0.15625 V, ±0.078125 V, software-configurable
Absolute maximum
input voltage
CxH-CxL relative to
GND
±30 V maximum (power on)
±10 V maximum (power off)
Input impedance
2 GΩ (power on)
390Ω (power off)
Input leakage current
±10.6 nA
Input voltage >±30 V
(power on/off)
±1 µA maximum
Input capacitance
590 pf
Maximum working
voltage (signal +
common mode)
Voltage mode: ±20 V
range
±20.01 V maximum
Voltage mode: all other
voltage input ranges
±10.25 V maximum
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
Adjacent channels
100 dB
Input coupling
DC
Channel gain queue
Up to 64 elements
Software-configurable channel and range
Warm-up time
45 minutes minimum
Open thermocouple
detect
Automatically enabled when the channel is configured for a
thermocouple sensor.