DIN rail I/O Modbus slave with 8 configurable analog inputs

  • I/O interface – remotable on RS485 fieldbus
  • 8 analog inputs, 16 bits, isolated and configurable
  • Voltage reading from μV range up to ±50V
  • Current reading from μA range up to ±24mA
  • Direct resistance reading up to 130kΩ
  • Thermocouples with internal / ext. compensation
  • RTD thermal resistances, 2 / 3 wires connection
  • No channels are lost in 3 wires connection
  • Direct temperature reading with NTC sensors
  • 12 bits channel with internal temperature sensor
  • RS485 serial port with high speed (1Mb/s max)
  • Modbus RTU protocol, configurable over RS485
  • CoDeSys libraries for configuration and use
  • PC tool for configuring and testing modules
  • Compact dimension on 17.5mm of DIN rail
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CODE: 099-8103 Category: Modbus compact I/O modules


Interface module with 8 analog inputs that can be individually configured in an arbitrary way. It can measure voltage, current, resistance and temperature using thermocouples, RTDs, and NTC.
It’s no longer necessary to purchase many products to realize a wide variety of different plants and acquisition systems. The EX08AI module not only covers the entire range of competitor products but offers unprecedented performance respect to products of similar price range. It uses two parallel 24bits ADCs filtered and decimated to obtain samples with 16bits resolution, while the processor applies complex formulas using floating point calculation, to linearize the temperature reading.
Easy integration in the “PLC Configuration” of CoDeSys tool in conjunction with the compact Web PLCs.
Ultra compact (only 17.5mm wide) realization with DIN rail mounting.

Channels configuration
Single-ended voltage ±50V, ±20V, ±10V, ±5V, ±2V
Differential voltage ±1V, ±0.5V, ±0.2V, ±0.1V, ±0.05V, ±0.02V, ±0.01V
Differential current ±20mA, ±10mA, ±5mA, ±2mA, 4÷20mA, ±24mA
Differential thermocouple E, J, K, N, R, T, S, B
RTD 2 / 3 wires thermal resist. Pt100, Pt200, Pt500, Pt1000, Ni100, Ni1000
NTC thermal resistance DKF103, 10K3435
Resistance 130kΩ, 30kΩ, 3kΩ, 300Ω
Potentiometer 1÷100kΩ

Technical Specification

Analog inputs 8 differential channels, 3V max from AGND
Max over-voltage ±80V (single-ended V), ±25V (other scales)
Isolation 1500Vac max (from bus and power supply)
Samples resolution 16 bits (from 2x Sigma-Delta 24 bits ADC)
Samples mean 62.5ms steps programmable (N = 1÷255)
Acquisition time 62.5ms min (2 channels), 250ms (8 channels)
Errors signalling Underflow / Overflow / sensor fault
Thermal drift 50 ppm/°C
Temperature sensor Internal NTC placed near input terminals
Conversion 12 bits ADC (indipendent from 8 channels)
Temperature reading -20°C to 80°C, 0.1°C resolution, ±0.5°C error
Fieldbus RS485 with EMI filter, thermal prot. / ESD 15kV
Max nodes / Termin. 64 / insertable 120Ω load
Baudrate 300b/s ÷ 1Mb/s (continuosly prog.)
Protocol Modbus RTU, address 1 ÷ 247, parity N/O/E
Function codes 3, 4, 6, 16, 17, 23, 100, 101, 102, 109, 110
Max performance Complete I/O update within 700μs (@ 1Mb/s)
Power supply 24Vdc ±15% / 60mA max
Operative temp. -20°C to 70°C
Connections Plug-in screw terminals 28÷12AWG / 2.5mm2
Box ABS with 35mm DIN rail mount / IP20
Max dimensions 113 x 17.5 x 119 mm (H x W x D)


EX08AI brochure
Modules configuration manual
Modbus-Tool for configuration and test