EX08AI channels configuration
The EX08AI modbus analog module has eight high resolution input channels, individually configurable to acquire various types of signal and analog sensor.
No product on the market offers the ability to measure voltages up to 50V so it is possible, for example, to read the 24Vdc power supply voltage or the status of a backup battery.
RTD sensors can be connected in two-wire or three-wire mode for the cable resistance compensation. In three-wire mode, however, all eight channels can be used unlike similar products that use two distinct channels for one sensor resulting in a reduction in the number of available channels.
For each type of analog sensor, different measurement scales can be set to obtain the best resolution for the specific application.
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Single-ended voltage
±50V, ±20V, ±10V, ±5V, ±2V
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Differential voltage
±1V, ±0.5V, ±0.2V, ±0.1V, ±0.05V, ±0.02V, ±0.01V
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Differential current
±20mA, ±10mA, ±5mA, ±2mA, 4÷20mA, ±24mA
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Thermocouple sensors
E, J, K, N, R, T, S, B
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RTD 2/3 wires sensors
Pt100, Pt200, Pt500, Pt1000, Ni100, Ni1000
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NTC sensors
DKF103, 10K3435
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Resistance
130kΩ, 30kΩ, 3kΩ, 300Ω
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Potentiometer
1÷100kΩ
Analog sensor connection
Each of EX08AI channels can measure the differential voltage, with high resolution, between the specific two screw terminals. For a three-wire connection (RTD and potentiometer) the AGND screw terminal is also used. The internal analog-to-digital converters can also measure the terminal voltages referred to the AGND terminal and the current circulating in the sensor. This information allows the measurement of the resistances of the analog sensor and the connecting cable.
The different types of measurement require the setting of four dip–switches that configure the internal hardware front-end. For each type of analog sensor, a specific configuration value must also be set via software, which defines the measurement scale. The documentation of EX08AI module shows the values to be used for the different sensors and scales.
Analog signal specifications
The EX08AI analog module is calibrated using a high-precision automatic system, specifically developed for EX08AI, that stores 14 parameters for each single channel inside the module permanent memory. These calibration values (a total of 112 points) results in a high precision of the measurement for all the measuring scales as follows:
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Single-ended voltage ±50V
Reading: ±10000
Resolution: 0.01% fs
Precision: ±0.05% fs -
Single-ended voltage ±20V
Reading: ±10000
Resolution: 0.01% fs
Precision: ±0.03% fs -
Single-ended voltage ±10V
Reading: ±10000
Resolution: ±0.01% fs
Precision: 0.03% fs -
Single-ended voltage ±5V
Reading: ±10000
Resolution: ±0.01% fs
Precision: ±0.05% fs -
Single-ended voltage ±2V
Reading: ±10000
Resolution: ±0.01% fs
Precision: ±0.08% fs
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Differential voltage ±1V
Reading: ±20000
Resolution: 0.005% fs
Precision: ±0.01% fs -
Differential voltage ±0.5V
Reading: ±20000
Resolution: 0.005% fs
Precision: ±0.01% fs -
Differential voltage ±0.2V
Reading: ±20000
Resolution: ±0.005% fs
Precision: 0.01% fs -
Differential voltage ±0.1V
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.02% fs -
Differential voltage ±0.05V
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.01% fs -
Differential voltage ±0.02V
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.02% fs -
Differential voltage ±0.01V
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.04% fs
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Differential current ±20mA
Reading: ±20000
Resolution: 0.005% fs
Precision: ±0.01% fs -
Differential current ±10mA
Reading: ±20000
Resolution: 0.005% fs
Precision: ±0.01% fs -
Differential current ±5mA
Reading: ±20000
Resolution: ±0.005% fs
Precision: 0.01% fs -
Differential current ±2mA
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.02% fs -
Differential current 4÷20mA
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.01% fs -
Differential current ±24mAV
Reading: ±20000
Resolution: ±0.005% fs
Precision: ±0.01% fs
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Resistor 130kΩ
Reading: 0÷65000
Resolution: 0.0016% fs
Precision: ±0.05% fs -
Resistor 30kΩ
Reading: 0÷30000
Resolution: 0.0033% fs
Precision: ±0.03% fs -
Resistor 3kΩ
Reading: 0÷30000
Resolution: 0.0033% fs
Precision: ±0.01% fs -
Resistor 300Ω
Reading: 0÷30000
Resolution: 0.0033% fs
Precision: ±0.03% fs
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Potentiometer 1÷100kΩ
Reading: 0÷10000
Resolution: 0.01% fs
Precision: ±0.05% fs
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NTC 10kΩ B=3960
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs -
NTC 10kΩ B=3435
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs
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Thermocouple type E
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.025% fs -
Thermocouple type J
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.025% fs -
Thermocouple type K
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.025% fs -
Thermocouple type N
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.025% fs -
Thermocouple type R
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs -
Thermocouple type T
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs -
Thermocouple type S
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs -
Thermocouple type B
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% fs
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Pt100 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.05% (±0.05%) fs -
Pt200 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.04% (±0.07%) fs -
Pt500 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.03% (±0.06%) fs -
Pt1000 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.025% (±0.05%) fs -
Ni100 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.08% (±0.16%) fs -
Ni1000 2 (3) wires RTD
Reading: 10 x °C
Resolution: 0.1°C
Precision: ±0.04% (±0.08%) fs