OMB-DAQ-2416-4AO User's Guide

Specifications

 

 

 

 

 

Parameter

Conditions

Specification

 

 

 

 

 

CJC sensor accuracy

15 °C to 35 °C

±0.15 °C typical

 

 

 

 

 

 

0 °C to 55 °C

±0.5 °C maximum

 

 

 

 

Note 1: Placing a notch of the A/D digital filter at 60 Hz (setting A/D data rate = 60 S/s, 10 S/s, 5 S/s or 2.5 S/s) further improves the common mode rejection of this frequency.

Channel configurations

When any item is changed, the firmware stores channel configurations in the EEPROM of the isolated microcontroller. An external application issues commands over the USB to make changes, and the configuration is made non-volatile through the use of the EEPROM.

When connecting differential voltage inputs to a floating voltage source, provide a DC return path from each voltage input to ground. To do this, connect a resistor from each input to a GND pin (pins 18, 36, 39, 42, 44, 46, 66, 81, 84). A value of approximately 100 kΩ can be used for most applications.

Leave unused input channels either floating or tied to GND (pins 18, 36, 39, 42, 44, 46, 66, 81, 84).

Source impedances should be kept as small as possible to avoid settling time and accuracy errors.

For each voltage/thermocouple channel configured as differential, you essentially lose one single-ended channel. You can add channels by connecting to an OMB-AI-EXP32.

 

 

Table 2. Channel configurations

 

 

 

Channel

Category

Specification

 

 

 

CxH/CxL

Thermocouple

16 differential channels

 

 

 

CxH/CxL

Voltage

32 individually-configurable channels that can be configured as either single-ended or

CxH/CxL

Voltage

differential.

 

 

 

Compatible sensors

 

Table 3. Compatible sensor type specifications

 

 

Parameter

Conditions

 

 

Thermocouple

J: -210 °C to 1200 °C

 

 

 

K: -270 °C to 1372 °C

 

 

 

R: -50 °C to 1768 °C

 

S: -50 °C to 1768 °C

 

T: -270 °C to 400 °C

 

 

 

N: -270 °C to 1300 °C

 

 

 

E: -270 °C to 1000 °C

 

 

 

B: 0 °C to 1820 °C

 

 

Accuracy

Thermocouple measurement accuracy

Thermocouple measurement accuracy specifications include polynomial linearization error, cold-junction compensation measurement error, and system noise. These specs are for one year, or 3000 operating hours, whichever comes first.

There is a CJC sensor for each terminal block of the module. The accuracy listed below assumes the screw terminals are at the same temperature as the CJC sensor.

The accuracy errors shown do not include the inherent accuracy error of the thermocouple sensor itself. Contact your thermocouple supplier for details on the actual thermocouple sensor accuracy limitations.

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