Horizontal Smart Controller 904 with Modular Design, Fully Digital Circuit & Industrial-Grade High-Performance MCU

Real-time liquid level acquisition and continuous data display, compatible with magnetostrictive level gauge, radar level transmitter, capacitance level switch and other common level sensors.

On-site parameter configuration, zero/span calibration and mode adjustment via front panel keys, independent operation without upper computer.

Multiple signal output options: 4–20mA analog output, multi-channel relay contact output and RS485 Modbus-RTU communication output, easy to connect with PLC, DCS and monitoring host.

Upper and lower limit liquid level alarm and interlock control; alarm trigger values and normally open/normally closed relay contacts can be freely set.

Local digital or LCD screen synchronously displays actual measurement value, percentage value and running state of equipment.

Built-in complete power protection mechanisms including reverse wiring, overvoltage, overload and short-circuit protection to safeguard controller and matched sensors.

Remote parameter modification, real-time data reading and equipment fault diagnosis through RS485 bus, suitable for centralized automatic control systems.

Automatic self-inspection after power-on; fault codes will be prompted on screen for quick positioning of sensor disconnection, signal overload and circuit faults.

Modular function expansion supports flexible upgrade of signal input and output channels according to on-site process requirements.

Stable data storage of alarm records and operation logs for historical data review and production traceability.

Petroleum & Petrochemical Industry Crude oil tanks, refined oil tanks, chemical solvent storage tanks and transfer pump stations for real-time level monitoring, high/low level interlock feeding and cut-off protection.

Fine Chemical Plants Reaction kettles, blending tanks, corrosive medium storage tanks, slurry tanks and dosing containers with closed-loop level control and over-limit safety alarm.

Municipal Water Supply & Wastewater Treatment Sedimentation tanks, clean water tanks, chemical dosing tanks, sewage lifting wells and reclaimed water tanks for automatic pump start-stop and remote centralized monitoring.

New Energy Sector Hydrogen auxiliary liquid tanks, thermal power condensate tanks, ash water pools and energy storage supporting tanks for reliable level measurement and safety interlock protection.

Food, Beverage & Edible Oil Processing Plants Edible oil storage tanks, brewing fermentation tanks, syrup and beverage mixing tanks requiring hygienic continuous level detection and quantitative batching control.

Pharmaceutical Factories Preparation tanks, raw material solvent tanks and intermediate transfer tanks with high-precision level control to guarantee formulation accuracy.

Metallurgy & Mining Mineral pulp tanks, circulating cooling water pools and process buffer tanks, adapting to strong electromagnetic interference and harsh on-site conditions.

Central Heating & Heat Exchange Stations Softened water tanks, expansion tanks and fuel storage tanks to realize automatic water replenishment and low-liquid-level protection.

Large Tank Farms, Ports & Logistics Storage Areas Unified access to PLC and DCS systems to realize unattended group tank monitoring and automatic safety interlock management.

The Horizontal Smart Controller 904 features modular design and full digital circuit architecture, perfectly matching magnetostrictive level transmitters, radar level meters, capacitance level switches and other liquid level sensors. It is widely adopted for on-site display, signal conversion, logic interlock control and remote centralized data collection in diversified industrial liquid storage and process measurement & control links.

Strictly follow the wiring diagram printed on the controller housing for wiring operation; never reverse the positive and negative poles of the power supply, otherwise the internal circuit will suffer permanent damage.

Confirm the signal type of the matched liquid level sensor (4–20mA DC current signal, resistance signal or switching signal) before powering on, and set the corresponding channel parameters on the controller to avoid signal acquisition failure.

The equipment shall work within the rated ambient temperature range. Do not deploy it for long-term operation in environments with high humidity, dense dust, flammable explosive gas or intense electromagnetic interference without protective measures.

It is forbidden to conduct wiring, disassembly or parameter modification under powered status, so as to avoid electric shock accidents and accidental misoperation of interlock logic on site.

The 4–20mA analog output loop must adopt the matched rated load resistance. Excessive load resistance will lead to distorted output signals and inaccurate remote data transmission.

Use shielded twisted-pair cables for RS485 communication wiring, and reliably ground the shielding layer at one end only to reduce signal attenuation and external interference during long-distance transmission.

Set reasonable high and low liquid level alarm thresholds and interlock logic according to actual process requirements; too narrow threshold range will trigger frequent false alarms continuously.

Regularly check whether the wiring terminals are loose or corroded. Poor contact will cause fluctuating measured values and intermittent alarm faults.

Do not touch components on the internal circuit board with conductive tools during maintenance, as static electricity will burn out the core chip and scrap the controller.

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

The controller adopts horizontal panel mounting mode; fix it firmly on the cabinet panel to prevent internal wiring loosening caused by long-term vibration.

Do not arbitrarily modify the factory preset fixed parameters without professional technical support, otherwise the original measurement and control performance cannot be restored.