The 4-20mA analog current loop is a universal standard widely used across many industries. This method is preferred for long-distance transmission and in noisy environments due to its reliability. The ease of use and cost-effectiveness of 4-20mA analog signals have made them a popular choice in industrial instrumentation. Unlike voltage signals, the current value does not drop over long cable runs, ensuring consistent and accurate data transmission. The Modbus 4-20mA Analog Input Card is specifically designed for monitoring transmitters with 4-20mA analog current outputs.
Many industrial transmitters—such as those for temperature, pressure, level, flow, and pH—feature 4-20mA analog outputs, making accurate measurement essential. The 4-20mA Analog Input Module provides a comprehensive and powerful solution for acquiring, converting, and transmitting analog data from various sensors and instruments to network monitoring and management systems. Equipped with 8 analog input channels (4-20mA), support for industrial Modbus RTU and Modbus TCP protocols, Ethernet port, and SNMP, this module delivers exceptional flexibility for engineers and professionals to seamlessly integrate analog data into their network infrastructure. The analog input card enables easy integration within industrial networks and simplifies data transfer to SCADA, HMI, PLC, and other control systems. Additionally, this analog input module supports IoT functionality with MQTT protocol, allowing secure and efficient data transmission for Internet of Things applications.
The 8-channel Modbus analog input card (4-20mA, Ethernet) is designed for precise monitoring and control of industrial processes. Due to the widespread use of transmitters with 4-20mA analog outputs in industrial environments, reliable measurement and monitoring of these sensors is essential. This analog input card receives 4-20mA signals from sensors and transmitters, converting them to digital values for processing by control systems. The CTV301 analog to Modbus converter supports Modbus TCP/RTU, Ethernet, MQTT, and SNMP protocols, enabling seamless data integration and communication with PLC systems, SCADA, and other automation equipment. With 8 independent analog input channels (4-20mA), this module allows connection to up to 8 transmitters or sensors. Certain models also feature a digital temperature sensor for enhanced monitoring.
Using the 4-20mA analog input module, you can easily measure sensor outputs and detect faults. If the current is outside the standard 4-20mA range (such as below 3.8mA or above 20.5mA), the system recognizes a sensor error. The 4-20mA current loop is widely used in oil and gas, petrochemical, food and beverage, and other industries due to its noise immunity, capability for long-distance transmission, fault detection, and compatibility with a wide range of automation equipment.
For portable 4-20mA sensor monitoring, see our Portable 4-20mA Measuring Device. If you need advanced features on your Modbus cards—including additional relay outputs and I/O ports—check out the Multi-Purpose Network Expansion Module, which offers 8 relays and versatile input/output options alongside 4-20mA analog inputs. For applications requiring both 4-20mA and 0-10V analog signal measurement, we recommend our Analog Voltage to Modbus Converter.
