ISO 4021 (LED1) Series 4-20mA 0-10V to RS485/RS232 Converter with LED Display

Product Advantage

1. High-Resolution Acquisition with Noise Rejection

The ISO 4021 (LED1) combines a 24-bit sigma-delta ADC with a sampling rate of 10 samples per second and a specified measurement accuracy of 0.05%. Typical temperature drift is ±15 ppm/°C, with a maximum of ±30 ppm/°C.

For measurements affected by electrical interference, the module provides 120 dB common-mode rejection and 60 dB normal-mode rejection under the stated 50/60 Hz test conditions. Digital filtering helps reduce power-frequency noise, while internal transient suppression diodes limit surge disturbances. Voltage inputs offer an impedance above 1 MΩ; current-input resistance depends on the selected range.

2. Selectable Protocols for Serial System Integration

Software configuration allows users to choose between ASCII communication and Modbus RTU. The ASCII instruction set offers ADAM-compatible commands, while Modbus RTU supports integration with controllers and supervisory systems that implement the corresponding register functions. Existing installations should be checked for command, wiring and configuration compatibility before replacement.

Eight baud-rate settings are available, from 300 to 38,400 bps. RS-485 communication supports cable runs of up to 1,200 meters under suitable installation conditions, with a specified response time below 100 ms. Actual network capacity and distance depend on the protocol, cable, termination, baud rate and connected devices.

3. Isolated Measurement Interface

A rated 3,000 VDC isolation barrier separates the analog input section from the communication and power-supply side. The specified withstand test lasts one minute at the stated 1 mA leakage condition. This separation helps manage ground-potential differences between field sensors and the receiving system.

Additional specifications include ±15 kV ESD protection at the serial interface and a listed impulse withstand rating of 3 kVAC with a 1.2/50 μs waveform. These features support industrial monitoring applications when combined with appropriate grounding, shielding and external surge protection.

4. Local Readout with Two Viewing Modes

The integrated four-digit LED display lets operators inspect channel readings at the module. In single-channel mode (C1), the channel-selection buttons determine which input is shown. Cyclic mode (C2) automatically alternates between channels for routine observation.

The display identifies the channel and presents its measurement value using the documented polarity indication. The MODE button switches viewing modes and allows the display to be turned off. This local readout assists commissioning and troubleshooting; precision verification still requires suitable external measuring equipment.

5. Wide Supply Range and Low Power Demand

An 8–50 VDC supply range accommodates nominal 12 V, 24 V and 48 V systems, provided the actual supply remains within the specified limits. Built-in reverse-polarity and overvoltage protection help address common power-input disturbances.

Power consumption below 1 W limits the module’s contribution to cabinet power demand and heat generation. The supply and serial interface share a common ground, while the analog input section remains isolated. This grounding arrangement should be considered when connecting sensors, controllers and other powered equipment.

Technical Parameters

Product Uses

Here are seven specific application scenarios of the ISO 4021(LED1) Series 2-Channel Analog AD Acquisition Display Control Isolation Transmitter:

1.Industrial equipment intelligent monitoring and maintenance: The module is used to acquire analog signals from industrial equipment sensors with 24-bit precision, display real-time measurements on the 4-digit LED digital panel, and transmit data via RS-485/RS-232 to a central control system, enabling remote equipment condition monitoring, predictive maintenance, and fault diagnosis with 3000VDC isolation protecting control circuits from field-side electrical interference.

2.Smart building and home automation systems: The module is used to collect analog signals from temperature, humidity, and environmental sensors deployed throughout smart buildings and home automation systems, converting them to digital data via A/D conversion and transmitting over RS-485 bus to building management systems, with multi-channel LED display providing on-site real-time monitoring and the wide 8-50VDC power supply accommodating various building power distribution conditions.

3.PLC and DCS analog signal acquisition: The module is used to interface field analog sensors with PLC and DCS control systems by performing high-precision A/D conversion and signal isolation, supporting both ASCII character protocol and MODBUS RTU protocol for seamless integration with various industrial control platforms, with up to 256 modules connectable on a single RS-485 bus covering communication distances up to 1200 meters for large-scale distributed control applications.

4.Petrochemical and environmental monitoring: The module is used to acquire and isolate analog signals from temperature, pressure, flow, and gas detection sensors in petrochemical plants and environmental monitoring stations, with 3000VDC isolation ensuring safe signal transmission between hazardous field areas and control rooms, while the industrial-grade temperature range of -40 to +85°C guarantees reliable operation in harsh outdoor and chemical processing environments.

5.Power automation and energy management: The module is used to monitor analog parameters from power distribution equipment including voltage, current, and power sensors, transmitting real-time data via RS-485 bus with MODBUS RTU protocol to power automation supervisory systems, with ±15KV ESD protection and transient suppression diodes safeguarding communication interfaces from high-voltage transients and surge pulses encountered in electrical power grid environments.

6.Transportation system intelligent control: The module is used to acquire analog signals from railway and highway monitoring sensors including track vibration detectors, toll weigh-in-motion sensors, and traffic flow monitors, converting field data to digital format for transmission to transportation control centers, with the dual communication interfaces supporting both RS-232 for local diagnostic connections and RS-485 for long-distance networked monitoring across transportation infrastructure.

7.Medical instrument data acquisition: The module is used to collect and isolate analog physiological sensor signals in medical monitoring and diagnostic equipment, with 3000VDC galvanic isolation serving as a safety barrier between patient-connected measurement circuits and digital processing systems, while the 0.05% measurement precision and 24-bit A/D conversion resolution ensure accurate acquisition of critical patient vital signs for real-time LED display and RS-485 data transmission to hospital information systems.