Three-Wire Isolated Analog to RS485 Data Acquisition Module ISOAD U(A)-P-485

Device features:

1. Protect the control loop of the upper stage of the host computer.

2. Reduce the impact of environmental noise on the test circuit, and can overcome inverter noise and various high and low frequency pulsation interference.

3. It suppresses the interference of circulating currents in public ground wires and pulses of frequency converters, solenoid valves, thyristors, etc. to equipment. It also has the function of limiting voltage and current for lower-level equipment. It is a faithful protection for transmitters, instruments, frequency converters, solenoid valves, PLC/DCS input and output, and communication interfaces.

The DIN35 series standard 35mm guide rail card holder structure is easy to install and can effectively isolate: the potential difference between signal input, signal output, power supply and earth.

Product Advantage

1. Compact Single-Chip Analog-to-Digital Signal Chain with Built-In RS-485 Modbus RTU Communication

The ISO AD U(A)-P-485 integrates the complete analog front-end, precision AD conversion, linearization, digital isolation, and fieldbus communication stack into a single SIP12 package. Sixteen standard input ranges are supported: U1 (0–5V), U2 (0–10V), U3 (0–75mV), U4 (0–2.5V), U5 (0–±5V), U6 (0–±10V), U7 (0–±100mV), A1 (0–1mA), A2 (0–10mA), A3 (0–20mA), A4 (4–20mA), A5 (0–±1mA), A6 (0–±10mA), A7 (0–±20mA), plus user-custom ranges U8/A8. The internal measurement engine produces signed integer values up to ±60,000, with linear mapping configurable via range-limit registers (address 0x11/0x13, adjustable from –1,999 to 9,999). The RS-485 port communicates via Modbus RTU protocol supporting function codes 03 (read holding registers), 06 (write single register), and 10 (write multiple registers), with device addresses spanning 1–254, baud rates from 1,200 to 19,200 bps (six settings), and an 8N1 data format default — a complete bus-connected measurement node in a footprint smaller than most standalone ADCs.

2. 3,000VDC Triple Isolation with Bipolar Signal Support and Polarity-Aware Conversion

The galvanic barrier architecture provides independent isolation between three domains: the auxiliary power supply, the analog signal input, and the RS-485 communication output — each rated at 3,000VDC withstand voltage. This triple-isolation topology prevents ground loops from forming between the field sensor, the local instrument power rail, and the remote host controller, a critical requirement in distributed monitoring systems where ground potential differences of tens or hundreds of volts are commonplace. The input stage directly accepts bipolar signals (±5V, ±10V, ±100mV, ±1mA, ±10mA, ±20mA) without external level-shifting or rectification circuitry, and the internal ADC reports negative values natively: readings below the zero-point threshold produce negative output data, while readings above produce positive output data — a genuine signed-measurement capability that accurately represents bidirectional physical phenomena such as differential pressure, bidirectional flow, and positive/negative temperature deviations.

3. 0.05% Accuracy with Configurable Digital Filtering and Field-Programmable Calibration

The module achieves a full-scale accuracy of 0.05% at room temperature and maintains a temperature coefficient of ≤50 ppm/°C across the rated –20°C to +60°C operating range, with extended survivability from –40°C to +85°C. A software-configurable digital filter (register 0x19, range 0–20.0) provides adjustable noise suppression — higher values increase filtering strength for electrically noisy environments, while lower values preserve response speed for fast-changing signals. A fast-calibration register (address 0x07) accepts 0x81 for low-point calibration and 0x82 for high-point calibration, enabling field recalibration without specialized tools. The decimal-point position (register 0x15, range 0–3) and range-limit registers allow the module to be scaled to match virtually any sensor transfer function, while the independent readout of both integer (register 0x40) and single-precision float (register 0x42) formats accommodates both resource-constrained embedded controllers and high-level SCADA software.

Technical Parameters

Product Uses

Here are seven specific application scenarios of the ISOAD U(A)-P-485 Series Three-Wire Isolated Analog Signal Data Acquisition Module:

1.Traditional transmitter and instrument digital intelligent upgrade: The module is used to upgrade traditional analog transmitters and instruments by converting their 05V/010V/15V/0±100mV/020mA/420mA output signals into digital data via high-precision A/D conversion, enabling RS485 Modbus-RTU communication with PLC/HMI systems, with 3000VDC triple isolation and programmable zero, full-scale, and alarm parameters allowing seamless integration into existing instrumentation without replacing the original sensors.

2.Industrial field automation remote control and monitoring: The module is used to acquire analog signals from temperature, pressure, flow, and rotation speed sensors in industrial manufacturing facilities, performing isolated A/D conversion and transmitting digital data via RS485 bus to PLC/DCS control systems for remote measurement and control, with the compact SIP12Pin package (33.1×15.5×10.4mm) enabling direct PCB mounting inside existing control equipment for space-efficient automation system upgrades.

3.Petroleum, chemical, and environmental monitoring systems: The module is used to collect analog signals from temperature, pressure, flow, and liquid level transmitters deployed across petroleum refineries, chemical processing plants, and environmental monitoring stations, with 3000VDC triple isolation ensuring safe signal transmission between hazardous field areas and control rooms, while the industrial-grade temperature range of -40°C to +85°C guarantees reliable operation in harsh outdoor and chemical processing environments.

4.Mining industry safety monitoring and control point measurement: The module is used to acquire analog signals from mining safety sensors including gas detectors, ventilation monitors, and structural pressure transmitters in underground and surface mining operations, with 3000VDC galvanic isolation protecting control systems from electrical hazards, and the programmable alarm output function enabling threshold-based safety alerts with configurable hysteresis timing for critical mining safety monitoring applications.

5.Power and gas equipment operation measurement and remote control: The module is used to monitor analog parameters from power distribution equipment and gas pipeline instrumentation, converting sensor signals to digital data via RS485 Modbus-RTU protocol for transmission to SCADA supervisory systems, with ±60000 programmable output range, 0.05% measurement precision, and ≤50PPM/°C temperature stability ensuring accurate and reliable long-term monitoring of utility infrastructure operation parameters.

6.PLC and DCS fieldbus data acquisition networks: The module is used to interface field analog sensors with PLC and DCS control systems by performing isolated A/D conversion and supporting standard Modbus-RTU protocol with 03/06/10 function codes, with device addresses from 1 to 254 plus broadcast and universal addresses enabling multi-module bus networks, and programmable baud rates from 1200 to 19200bps supporting flexible integration with various industrial communication infrastructures.

7.Medical instrument and industrial control equipment product development: The module is used as a core data acquisition component in medical instruments and industrial control equipment development, providing isolated high-precision analog signal acquisition with programmable range scaling, alarm output control, and digital filtering coefficients, with the low-cost small-form-factor design and reverse/overcurrent protection enabling rapid prototyping and volume production of intelligent measurement and monitoring devices for medical and industrial control applications.