The Challenge: Monitoring Rooftop & Underground Tanks
Water tanks are typically located in the most difficult-to-reach places: on rooftops (5-15 floors up) or underground sumps. Running cables vertically through building structure or underground trenching is expensive, time-consuming, and often requires building modifications.
🏗️ Installation Challenges
- Rooftop tanks 50m to 150m above ground floor
- Vertical cable runs through elevator shafts or external conduits
- Underground sumps requiring trenching
- Multiple tanks distributed across campus
⚠️ Operational Problems
- Manual checks require personnel to climb to roof or basement
- Overflow wastes water and causes damage
- Dry running damages pumps
- No visibility into tank status from control room
The Solution: Wireless Level Monitoring
Link485 wireless Modbus gateways connect your existing Modbus level sensors (ultrasonic, pressure, float) to the cloud or BMS using LoRa with excellent vertical penetration (up to 1km vertically) - no cables needed.
What You Can Monitor
Tank Parameters
- Current level (mm, cm, or %)
- Volume (liters or m³)
- High level alarm (90%+)
- Low level alarm (10%-)
- Overflow detection
Pump Control
- Auto start pump when level < 20%
- Auto stop pump when level > 90%
- Dry run protection
- Pump runtime hours
- Energy consumption tracking
Alerts & Notifications
- SMS/Email when tank is empty
- WhatsApp alerts for overflow
- Pump failure notifications
- Abnormal consumption alerts
- Daily summary reports
Common Modbus Level Sensors
Ultrasonic Level Sensor
Range: 0.3m to 15m
Accuracy: ±0.5%
Best For: Rooftop water tanks, clean water
Holding Register 40001: Level (mm)
Holding Register 40002: Distance (mm)
Input Register 30001: Alarm Status
Submersible Pressure Sensor
Range: 0 to 100m water column
Accuracy: ±0.25%
Best For: Underground sumps, deep tanks
Holding Register 40101: Pressure (mbar)
Holding Register 40102: Level (m)
Holding Register 40103: Temperature
Radar Level Sensor
Range: 0.1m to 30m
Accuracy: ±3mm
Best For: Any liquid, works in dust/vapor
Holding Register 40201: Level (mm)
Holding Register 40202: Volume (L)
Input Register 30201: High Alarm
Wiring Diagram: Rooftop Tank Monitoring
Install Link485 Zero on the rooftop near the tank. Connect RS-485 from the level sensor and pump controller. The gateway transmits data wirelessly down to the base station in the control room (up to 1km vertical range).
Automated Pump Control Logic
// Pump Auto-Start Logic
IF (Tank_Level < 20%) AND (Sump_Level > 30%) THEN
START Pump
Log: "Auto-started pump - Tank Low"
END IF
// Pump Auto-Stop Logic
IF (Tank_Level > 90%) OR (Sump_Level < 10%) THEN
STOP Pump
IF (Sump_Level < 10%) THEN
ALERT: "Dry run protection activated"
END IF
Log: "Auto-stopped pump"
END IF
// Overflow Prevention
IF (Tank_Level > 95%) THEN
FORCE STOP Pump
ALERT: "CRITICAL - Overflow imminent"
END IF
Case Study: Apartment Complex (12 Towers)
Multi-Tower Residential Complex - Rooftop Tank Monitoring
A 12-tower residential complex in Bangalore needed to monitor 24 rooftop tanks (2 per tower) and 12 sump tanks. Running cables from each rooftop down 15 floors to the central pump room would have required extensive cabling through elevator shafts, which would be costly and disruptive.
"Link485 Zero saved us from running cables down 15 floors across 12 buildings. We completed installation in 2 weeks vs 3 months for wired. Overflows reduced to zero, and residents get alerts on their phones when tanks are filling." — Facility Manager, Residential Complex
Configuration Steps
Install Level Sensor
Mount ultrasonic sensor on tank top or submersible sensor at tank bottom. Connect RS-485 output.
Mount Link485 Gateway
Install Link485 Zero near the tank (within 10m of sensor). Use weatherproof enclosure if outdoors.
Wire RS-485 Connection
Connect A, B terminals from sensor to gateway. Include pump controller if automating pump control.
Install Base Station
Place Link485 base station in control room. Gateway auto-pairs on power-up (zero configuration).
Configure Cloud Dashboard
Use Link485 Cloud to set tank dimensions, alarm thresholds, and pump control logic.
Setup Alerts
Configure SMS/email/WhatsApp alerts for low level, overflow, pump failures, and daily reports.