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32-Channel USB/IP Based Thermocouple Data Acquisition System

32-Channel USB/Ethernet Based Thermocouple Input Data Acquisition System
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1-4 $2,956.24
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32-Channel USB/Ethernet Based Thermocouple Input Data Acquisition System OMB-DAQ-TC-RACK OMB-DAQ-TC-RACK
  • USB and 10/100 Ethernet Interface
  • 32 Differential Thermocouple Inputs
  • Expandable to 64 Thermocouple Inputs with OMB-DAQ-TC-RACK-EXP32 Expansion Module
  • Thermocouple Channel-to-Host Isolation

OMB-DAQ-TC-RACK Model Options

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Analog Input Type
Analog Input Class
Number of Analog Inputs
Input Range
Output Type
Number of Outputs
Output Range
Digital I/O
Interface Protocol

The OMB-DAQ-TC-RACK and OMB-DAQ-TC-RACK-EXP32 offer exceptional performance and accuracy for thermocouple measurement applications at a low cost per channel. Offering both Ethernet and USB ports, the OMB-DAQ-TC-RACK provides 32 channels of 24-bit resolution for medium channel installations. The OMB-DAQ-TC-RACK-EXP32 adds 32 high-precision channels to support larger installations. Accuracy is designed into the product with sigma-delta 24-bit ADCs, differential inputs, thermocouple-to-host isolation and cold-junction compensation (CJC) for each channel to reduce the effects of thermal gradients. With digital alarming notifications when a temperature exceeds programmed limits, the OMB-DAQ-TC-RACK and OMB-DAQ-TC-RACK-EXP32 offer the perfect solution for temperature monitoring applications including server rooms, refrigerated storage, and long-run test cells.

(Typical for 25°C (77°F) unless otherwise specified)
These specifications apply to both the OMB-DAQ-TC-RACK and OMB-DAQ-TC-RACK-EXP32 unless noted otherwise.
Thermocouple Input
A/D Converter Type: Delta-Sigma
A/D Resolution: 24-bit
Number of Channels: 32 (64 when OMB-DAQ-TC-RACK is connected to OMB-DAQ-TC-RACK-EXP32)
Filtering Options: 50 Hz or 60 Hz noise filtering, software-selectable
Isolation Between Any Thermocouple Input Channel and Chassis Ground: 500 Vdc absolute max
Channel Configuration: Software-selectable to match thermocouple sensor type
Differential Input Voltage Range: ±78.125 mV
Absolute Maximum Input Voltage (Between any Two TCx Inputs): ±25V (power on), ±25V (power off)
Differential Input Impedance:
    50 Hz Filtering, Power On: 26 M?
    60 Hz Filtering, Power On: 20 M?
Input Current:
    Open Thermocouple Detect Disabled: 2 nA
    Open Thermocouple Detect Enabled: 75 nA
Common Mode Rejection:
    50 Hz Filtering at DC and fIN=50 Hz: 110 dB
    60 Hz Filtering at DC and fIN=60 Hz: 110 dB
Noise Rejection:
    50 Hz Filtering at fIN=50 Hz: 80 dB typ
    60 Hz Filtering at fIN=60 Hz: 80 dB typ
Input Bandwidth:
    50 Hz Filtering: 22 Hz
    60 Hz Filtering: 26 Hz
Crosstalk Between Any Two Thermocouple Inputs: -90 dB
Sample Rate: 3 Hz max (per channel); the enabled thermocouple inputs are continuously converted at the maximum A/D converter rate
Common Mode Voltage Range:
    TCx Channel to TCx Channel: ±1.40V
    TCx Channel Relative to Chassis Ground, fIN = 60 Hz: ±3.5 Vac p-p
    TCx Channel Relative to Chassis Ground: ±48 Vdc
When thermocouple sensors are connected to different common mode voltages, the channels with floating thermocouples sensors are biased to approximately the average value of the applied common mode voltages. Each of the applied common mode voltages must then be less than or equal to the average common mode voltage ±1.40 V or [CMVapplied = (CMVaverage ±1.4 V)].
Input Noise (50 or 60 Hz Filtering): 510 nV rms
Gain Error (50 or 60 Hz Filtering): 0.004% FSR
Offset Error (50 or 60 Hz Filtering): 3 µV
Measurement Sensitivity (Smallest Change in Temperature That Can Be Detected):
    Thermocouple Type J, K, T, E, N: 0.05°C
    Thermocouple Type R, S: 0.10°C
    Thermocouple Type B: 0.15°C
Warm-Up Time: 20 minutes min
Open Thermocouple Detect Response Time: 1 s
CJC Sensor Accuracy (0 to 45°C): ±0.20°C typ, ±0.40°C max
Channel Configuration
Thermocouple (J, K, T, E, R, S, B, N): 32 differential channels Channel configuration is stored on EEPROM external to the isolated microcontroller by the firmware whenever any item is modified. Modification is performed by commands issued from an external application, and the configuration is made nonvolatile through the use of the EEPROM.

Digital Input
Number of Inputs: 8 channels (16 when OMB-DAQ-TC-RACK connected to OMB-DAQ-TC-RACK-EXP32)
Configuration: Fixed input
Input Voltage Range: 0 to 15V
Input Type: CMOS (Schmitt trigger)
Input Characteristics: 100 k? pull-up resistor, 28.7 k? series resistor
Maximum Input Voltage Range: 0 to 20V max (power on/off, relative to IGND pins)
Pull-Up Configuration: All pins pulled up to 5V via individual 100 k? resistors using slide switch SW5; SW5 default position are on (pulled up)
Transfer Rate (Software Paced): 500 port reads per second typ
Input High Voltage: 1.3V min, 2.2V max
Input Low Voltage: 1.5V max, 0.6V min
Schmitt Trigger Hysteresis: 0.4V min, 1.2V max

Digital Output
Number of Outputs: 32 channels, shared with alarms (64 when OMB-DAQ-TC-RACK connected to OMB-DAQ-TC-RACK-EXP32)
Configuration: Open drain output
Output Characteristics: 100 k? pull-up, open drain (DMOS transistor)
Pull-Up Configuration: All pins pulled up to 5V through individual 100 k? resistors using slide switches SW1-SW4; the default positions for SW1-SW4 are on (pulled up)
Transfer Rate (Software Paced): Digital output–500 port writes per second typ
Output Voltage Range:
    0 to 5V: Internal 100 k? pull-up resistors connected to 5V by default
    0 to 15V: Max (using external pull-up resistor)
Ground: Pins labeled IGND are isolated from AGND and chassis ground
Off State Leakage Current: 0.1 µA
Sink Current Capability: 100 mA max (continuous) per output pin
DMOS Transistor On-Resistance (Drain to Source): 4 O

Operating Temperature Range: 0 to 45°C (32 to 113°F)
Storage Temperature Range: -40 to 85°C (-40 to 185°F)
Humidity: 0 to 90% RH non-condensing
Dimensions: 482.6 L x 128.6 W x 43.18 mm H (19 x 6.15 x 1.74")
Weight: OMB-DAQ-TC-RACK: 3.8 lb (1.73 kg); OMB-DAQ-TC-RACK-EXP32: 3.2 lb (1.45 kg)
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Is the ethernet communication protocol publicly available? We would like to communicate with the DAQ directly from an embedded application, without universal library. Thank you

Asked by: Milanraf
Thank you for your question. Please e-mail your question to our Das Engr Dept, DAS@OMEGA.COM.
Answered by: Raptor
Date published: 2020-07-15

Can you purchase the item calibrated to NIST?

Asked by: Rusty
OMB-DAQ-TC-RACK is calibrated with NIST traceable equipment, but at this moment calibration cert is only included when requested at the time of purchase. After discussing with the product manager we decided to include the cert on all future batches at no additional cost. Please email us at if you have any further questions.
Answered by: Jane
Date published: 2019-05-21

Is the software compatible with Windows 10?

Asked by: Rusty
Thank you for your question. Yes, software is compatible with WINDOWS 10.
Answered by: VPDAS
Date published: 2020-04-06

How well do the OMB-DAQ-TC-RACK devices interface with a PLC? What is the minimum time to read in all 32 channels? I know I can expand to 64 channels but how about +/- 300 channels. Would 300 channels require (5) 64 channel setups?

Asked by: AlanAtTrane
Thanks for connecting with Omega. This unit is not designed to interface with a PLC. The max sample rate is 3 hz per channel. There is no provision for more than 64 inputs so you would need multiple setups and multiple computers running the software to do anything more than 64 channels. Please contact our Tech Support if you need further assistance finding a product to fit your application needs.
Answered by: Jane
Date published: 2019-05-22

Will this interface to a SCADA system over Ethernet I/P such as Ignition (Inductive Automation) for data acquisition?

Asked by: GDG1
Hello It will not interface to a SCADA system. You will need to use our universal library which is included in the software CD to communicate with the OMB-DAQ-TC-RACK.
Answered by: JA Engineer
Date published: 2019-08-28
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