RS485 Modbus RTU pH ORP Controller with Dual 4-20mA Output and IP66 Panel Mount for Online pH ORP Analyzer

The APX1-C2 online pH/ORP controller is a panel-mount, continuous-analysis instrument designed to measure and control the pH or ORP value of aqueous solutions in water treatment, chemical processing and industrial automation. Built around a 3.2 inch graphic LCD and a 32-bit processing core, it delivers stable, low-drift readings and communicates them through a flexible mix of digital and analog interfaces.

Its RS485 interface supports both standard Modbus RTU protocol and JSON text format. In addition, two active 4~20mA / 0~20mA outputs (max. load 1000Ω) allow the measured value and temperature to be mirrored to legacy analog recorders, and two SPST relays provide direct control of dosing pumps, valves and alarms. The result is a single instrument that measures, displays, transmits and controls pH/ORP in one compact, IP66 protected package.

Typical users include municipal and industrial wastewater plants, pure water and drinking water facilities, food & beverage processors, electroplating and PCB lines, and aquaculture farms that need dependable, networkable water-quality data.

1. Dual-protocol digital output: one RS485 port speaks both Modbus RTU and JSON, so the same controller fits PLC, SCADA projects.
2. Modbus RTU slave support: the host can read temperature, pH and ORP registers with function code 04 using a clearly documented register map.
3. Two active 4~20mA outputs: max. load 1000Ω, assignable to main value and temperature for legacy analog loops.
4. High accuracy and resolution: pH ±0.02 pH and ORP ±2 mV at 0.01 pH / 1 mV resolution.
5. Automatic temperature compensation: NTC10K or PT1000, automatic or manual, keeps readings stable across -10~+150 ℃.
6. Rugged IP66 panel-mount housing: compact 100*100*120 mm enclosure with power-failure protection that retains parameters indefinitely.

• Municipal and industrial wastewater treatment — aeration, neutralization and discharge monitoring
• Pure water, drinking water and surface water quality monitoring
• Chemical, petroleum and paper processing lines
• Electroplating and PCB manufacturing rinse-water control
• Aquaculture, fish farming and swimming pool water quality
• Food & beverage CIP (clean-in-place) monitoring

Interested in the APX1-C2 for your project? Contact Daruifuno today for samples, pricing and the Modbus register documentation.