Square Smart Controller 905 with Modular Design, Fully Digital Circuit & Industrial-Grade High-Performance MCU

Liquid level continuous measurement and real-time display, supporting multiple sensor access including magnetostrictive level gauge, radar level meter, capacitance level switch and other level instruments.

On-site local parameter setting, calibration, zero/span adjustment and working mode switching via keys or touch screen, no need for upper computer auxiliary operation.

Multiple standard signal output: 4–20mA analog signal, relay contact switch output, digital RS485 (Modbus-RTU) communication output, convenient for PLC, DCS and industrial touch screen interconnection.

High/low liquid level alarm, upper/lower limit interlock control function; freely set alarm threshold, support normally open / normally closed contact mode selection.

Data storage and historical curve recording: store level change data, alarm records and operation logs, realize historical data query and curve playback.

Temperature compensation algorithm built-in, automatically correct level measurement deviation caused by medium temperature change, improve long-term measurement stability.

Overvoltage, reverse wiring, short-circuit and overload protection functions, effectively protect the controller and front-end measuring sensors.

Remote parameter modification, data reading and fault diagnosis through RS485 bus, suitable for centralized automatic control system in chemical, petroleum, water treatment and storage tank industries.

Dual display mode: local digital tube / LCD real-time display measured value, percentage value and equipment running status simultaneously.

Self-check and fault code prompt function; automatically judge sensor disconnection, signal overload and internal circuit abnormality, and output corresponding fault codes for quick maintenance.

Petroleum and petrochemical industry Storage tanks for crude oil, refined oil, fuel oil and various chemical solvents; automatic liquid level monitoring, high-low level interlock feeding and cut-off control.

Chemical processing plants Reaction kettles, buffer tanks, storage tanks for acid, alkali, corrosive liquids and slurry; liquid level closed-loop control and over-limit safety alarm.

Water supply & wastewater treatment Raw water tanks, sedimentation tanks, clean water tanks, dosing tanks, sewage collection wells; liquid level automatic pump start-stop and remote monitoring.

Food & beverage industry Edible oil storage tanks, wine tanks, syrup tanks, beverage mixing tanks; hygienic liquid level continuous measurement and quantitative feeding control.

Energy and new energy industry Biomass liquid storage tanks, hydrogen storage auxiliary liquid tanks, thermal power plant ash water tanks, condensate tanks; stable level monitoring and interlock protection.

Pharmaceutical factories Preparation tanks, solvent storage tanks, intermediate transfer tanks; precise liquid level control to ensure production batching accuracy.

Port, oil depot and tank farm Large-area centralized tank group unattended monitoring system; unified access to DCS/PLC for centralized data acquisition and management.

Metallurgy and mining Mineral pulp tanks, circulating water tanks, cooling water pools; anti-interference level measurement under harsh industrial on-site conditions.

Heating & central heating system Heat exchange station expansion tanks, softened water tanks, fuel storage tanks; automatic replenishment and low-level protection control.

The 905 intelligent controller is specially designed to match various level measuring instruments such as magnetostrictive level transmitters, radar level meters and capacitance level switches. It is widely applicable to continuous liquid level detection, local display, logic interlock control, signal transmission and remote centralized monitoring of liquid storage equipment in multiple industrial sectors.

Wiring must strictly follow the wiring diagram printed on the product housing; positive and negative power supply cannot be reversed, otherwise the internal circuit may be permanently damaged.

Confirm the input signal type of the matched level sensor (4–20mA, resistance signal, switching signal) before power-on, and set the corresponding channel parameters on the controller to avoid signal acquisition failure.

The operating ambient temperature shall be kept within the specified range. Avoid long-term use in environments with high humidity, heavy dust, flammable and explosive gas or strong electromagnetic interference without protective measures.

Do not conduct wiring, disassembly or parameter modification when the equipment is powered on, to prevent electric shock and accidental equipment interlock misoperation.

The 4–20mA output loop needs to match the correct load resistance; excessive load will cause distortion of the analog output signal and inaccurate remote data transmission.

RS485 communication wiring shall use shielded twisted pair cable. The shielding layer shall be reliably grounded at one end to reduce signal attenuation and external interference in long-distance transmission.

Set reasonable high/low level alarm thresholds and interlock logic according to on-site process requirements; excessively narrow threshold setting is easy to trigger frequent false alarms.

Regularly check whether the wiring terminals are loose or corroded; poor contact will lead to unstable measurement values and intermittent alarm faults.

Do not use conductive tools to touch the internal circuit board components during maintenance; static electricity may burn out the chip and damage the controller.

If fault codes appear on the display screen, cut off the power supply first for inspection. Do not repeatedly power on and reset blindly, which may expand the fault range.

The equipment shall be installed vertically and fixed firmly on the cabinet panel or installation support to avoid vibration leading to loose internal wiring.

It is forbidden to arbitrarily modify the built-in fixed factory parameters without professional technical guidance, otherwise the original measurement and control performance cannot be restored.