Add wireless sensors to the SCADA you already own.
Most small water systems and plants run on SCADA hardware that reads sensors over 4–20 mA wire pairs — rugged, proven, and completely full. When the input channels run out, or a buried signal line gets cut, the traditional fix is trenching cable and adding I/O hardware. Meterra's approach is different: a small Modbus gateway lets your existing SCADA read our wireless field sensors as if they were wired in — turning one input port into capacity for hundreds of readings.
The problem: a full panel and aging wire
Most small water systems, treatment plants, and industrial sites run SCADA hardware that has earned its keep for decades. It reads its sensors over 4–20 mA current loops — one dedicated pair of wires per sensor, where the current itself is the measurement. Rugged, immune to most interference, and dead simple.
But that design has two hard limits, and operators hit both:
- The panel runs out of inputs. Every wired sensor consumes a physical channel. When they’re gone, adding “just one more tank” means new I/O hardware and often a controls project.
- The wire is the weak point. A buried signal run that gets cut — by construction, erosion, or age — doesn’t just take a reading off the screen. If automation ran on that reading, the automation goes with it, and trenching a replacement line can cost tens of thousands of dollars.
We’ve watched it happen to a real customer: Huntsville Town, Utah lost the wired SCADA line to a million-gallon tank a mile up a steep hill — a $50–80k trench to replace. A wireless Meterra sensor put the level back on screen for a fraction of that. The next phase we’re working toward with that same system is the subject of this page: feeding the wireless reading back into the plant’s SCADA, so the automation that used to run on the wired signal can run again.
How the bridge works, in plain English
Step one — the sensors go wireless. Meterra field sensors (ultrasonic or submerged pressure) mount at the tank, pond, or lagoon and report over low-power cellular. No trench, no conduit, no new wire runs.
Step two — a small gateway joins your plant. An industrial gateway — a small, Raspberry-Pi-class computer — sits at the facility and receives the wireless readings.
Step three — your SCADA reads them like local sensors. The gateway presents every reading to your existing SCADA over Modbus, the industry-standard protocol nearly every system already speaks. Where 4–20 mA is one lane per sensor, Modbus is a numbered mailbox wall: one connection, hundreds of addressed values. Your SCADA polls the gateway the same way it polls any local device.
Step four — your integrator maps the registers. Your SCADA software vendor or integrator tells the system what each address means (“register 12 is the hilltop tank level”). That’s a configuration change — parameters, not construction — and we coordinate it with them directly.
The result: one input port becomes capacity for hundreds of readings, the plant’s automation logic stays exactly where it lives today, and the sensors feeding it no longer depend on decades-old buried wire.
What this is — and isn’t
This is an engineering-supported integration, scoped per system with our engineering team and your SCADA integrator — not an off-the-shelf gadget. It supplies monitoring inputs to your system; control decisions stay in your SCADA, under your operators, exactly as they are now. Every project starts with a conversation about what you run, what the panel looks like, and whether cellular coverage reaches your sites — before anything is quoted or shipped.
If your input panel is full, a signal line is down, or a major I/O addition is on the capital plan, tell us about your system — it’s worth a call before you trench.
The hardware for this job
Every device reports to the same Meterra dashboard and app.
Tell us your site and we'll map the right sensors and coverage.
Frequently asked questions
What does "4–20 mA" actually mean?
It's how most older SCADA systems read a sensor. Each sensor gets its own pair of wires, and the amount of electrical current flowing on them — between 4 and 20 milliamps — is the reading itself. 4 mA means empty or zero, 20 mA means full, and everything between scales in proportion. It's simple and nearly bulletproof, which is why it's still everywhere — but every sensor needs its own dedicated wire run, and the control panel only has so many input channels.
What is Modbus, in plain terms?
Modbus is a simple industrial "language" from 1979 that almost every SCADA system still speaks. Instead of one pair of wires per sensor, one connection carries many addressed readings — the SCADA asks "device 12, what's your level?" and gets a number back. That's the trick that turns a single port into room for hundreds of values instead of one.
Does this replace our SCADA system?
No — that's the point. Your SCADA, your control logic, and your operator screens stay exactly as they are. The gateway simply hands your existing system additional readings over Modbus, as if they were locally wired sensors. You avoid both the cost of I/O expansion and the risk of a rip-and-replace project.
What has to change on our SCADA side?
Your SCADA software vendor or integrator maps the new Modbus registers — telling the system "this address is the hilltop tank level" — which is a configuration change, not a rewiring project. It's typically straightforward, and we work directly with your integrator to scope it before anything is installed.
Can this restore automation after a signal line is cut or fails?
That's one of the main cases we built it for. When a wired sensor line fails, the plant doesn't just lose a number on a screen — it can lose the automation that ran on that number, like a treatment plant pausing and resuming on tank level. Replacing the broken run with a wireless sensor and feeding the reading back in over Modbus gives the existing automation its input back, without trenching a new line.
How many sensors can one gateway carry?
Hundreds of readings are possible through a single Modbus connection — the practical number depends on your SCADA software and how often it polls. For a system whose input panel is maxed out, the difference is stark - adding wired channels means new I/O hardware for each handful of sensors, while the gateway approach adds capacity through the port you already have.
What does it cost?
The field sensors are our posted launch prices ($299–$499 each, including three months of connectivity). The gateway and integration work are scoped per system — because every SCADA setup is different — and quoted before anything ships. Tell us what you run and where the panel stands, and we'll give you real numbers.
Related Meterra solutions
- Water System Automation — when there's no SCADA at all — the site runs on the Meterra platform.
- Water District Monitoring — the wider story for small and rural water systems.
- Chemical & Dosing Tank Monitoring — treatment and dosing tanks on the same platform.
- Wastewater Lagoon Monitoring — lagoon levels for compliance and operations.
- Tank Level Sensor — the wireless ultrasonic sensor your SCADA would read.
- Grants & Funding Guide — programs that help small systems pay for upgrades.