4 Channel 20mA Modbus UIO-4IN-20mA

4 Channel 20mA Modbus Module

4-Channel Analog Input

The 4 Channel 20mA Modbus Module provides a compact solution for monitoring multiple industrial 0–20mA signals through a Modbus RTU network. The Veawe UIO-4IN 20MA-12 is a 4-channel analog input module with four 0–20mA inputs and configurable alarm logic. It connects current-output transmitters and sensors to PLCs, SCADA systems, HMIs, and industrial controllers through RS-485 communication.

The module provides 12-bit analog resolution with raw analog value resolution of 0.001mA. It represents the measured current as an integer value, where 0mA corresponds to 0, 4mA corresponds to 4000, and 20mA corresponds to 20000. This provides precise digital representation of standard industrial current signals.

Accurate Signal Monitoring and Scaling

The 4 Channel 20mA Modbus Module supports individual offset and gain calibration for each analog input. The module can provide raw analog values as well as scaled engineering values through Modbus registers. IEEE754 floating-point registers support engineering units such as pressure, temperature, tank level, flow, weight, and percentage.

Users can scale a 4–20mA transmitter to the required engineering range. For example, the module can convert a 4–20mA pressure transmitter into a 0–10 bar value. It can also scale tank-level and temperature transmitters into percentage or temperature values.

Analog Alarm and Sensor Fault Detection

The module provides configurable alarm logic for each analog input. Users can configure minimum and maximum alarm limits and select different alarm modes, including minimum-only, maximum-only, outside-window, and inside-window monitoring.

The 4 Channel 20mA Modbus Module also detects an open or disconnected analog sensor. When the module detects an open sensor, it reports the corresponding sensor-open status through Modbus and indicates the analog value as 0.000mA. Latched alarm status remains active until the Modbus master reads the status, helping the controller identify alarm events that may have already cleared.

Modbus RTU over RS-485

The module communicates through Modbus RTU over RS-485. It supports baud rates from 300 to 115200 and provides selectable serial formats. A rotary address switch allows Modbus address selection from 1 to 99. The default communication configuration is 19200 baud with 8N1 format.

Dedicated Modbus registers provide access to live analog values, scaled values, alarm status, sensor-open status, alarm counters, calibration parameters, and alarm limits. This gives automation systems direct access to both process measurements and diagnostic information.

Industrial 20mA Applications

The module operates from a 15–24V DC supply and provides four 0–20mA analog input channels. The terminal arrangement provides separate positive and negative connections for all four inputs. The module supports DIN rail mounting and uses a compact 110mm × 50mm × 55mm enclosure.

The 4 Channel 20mA Modbus Module is suitable for industrial process monitoring, pressure measurement, temperature monitoring, tank-level measurement, flow monitoring, and other applications that use 0–20mA or 4–20mA transmitters.