4CH Modbus to 20mA Analog Output – UIO-4AO

The Modbus to Analog Output module provides a simple way to connect Modbus RTU systems with analog control devices. The Veawe UIO-4AO 20mA is a compact Modbus RTU remote I/O module with four 0–20mA analog output channels. It communicates through RS-485 and supports Modbus RTU for reliable industrial communication.

The module converts Modbus data into precise analog current outputs. Each channel supports a 0–20mA output range. The module provides 0.02mA output resolution. It also supports individual offset and gain calibration for each analog output channel. This allows users to match the output signal with the requirements of connected field equipment.

The Modbus to Analog Output module supports both integer and IEEE754 floating-point values. Users can write raw analog values or scaled engineering values through Modbus registers. The module provides dedicated registers for AO1 to AO4. It also provides separate calibration registers for offset and gain adjustment.

The module can operate as a Modbus Server or Modbus Master. In Server mode, a PLC, SCADA system, HMI, or other Modbus client can control the analog outputs. In Master mode, the module can read values from another Modbus device. It then updates its analog outputs automatically. This makes the module useful for Modbus-to-analog signal conversion and analog retransmission applications.

Master mode can convert remote Modbus values into analog signals. Typical applications include converting temperature values into analog outputs. It can also send PLC values to legacy analog equipment. Users can use it for tank level, pressure, and flow signal retransmission. The module can also serve as a compact Modbus-to-analog gateway.

The module supports a wide range of baud rates from 300 to 115200. It provides configurable serial formats and a rotary address switch for device addressing. The default communication setting is 19200 baud with 8N1 format.

The built-in watchdog can reset the outputs to their initial safe state when Modbus communication fails. Users can configure the watchdog timeout from 1 to 600 seconds. This feature helps maintain a defined output state during communication faults.

The module also supports engineering-value scaling. Users can represent process values such as pressure, temperature, tank level, flow, weight, and percentage. IEEE754 floating-point registers provide convenient access to scaled values.

With its four analog outputs, RS-485 interface, Modbus RTU communication, calibration functions, and Master mode capability, the UIO-4AO 20mA provides a practical solution for industrial automation systems that need to connect digital Modbus data with analog 0–20mA control signals.

Configuration Software

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