The problem with managing silos without telemetry
An industrial silo without a remote monitoring system is a black box. The production or logistics manager has no idea how much material remains until someone physically checks — or, in the worst case, until the production line stops due to a shortage. This dependence on manual inspection generates unnecessary costs: reactive supply routes instead of planned ones, expensive emergency orders, avoidable site visits and downtime that directly erodes margin.
The problem is especially acute in installations with geographically distributed silos — multi-site production plants, farms with feed tanks across different locations, or chemical and cement companies with storage points spread across a region. In all these cases, a silo telemetry system built on Wago PLC and Codesys shifts the operation from reactive to proactive, with real-time information available from anywhere.
Why Wago PFC200 + Codesys for silo telemetry
Choosing the right controller for a silo telemetry system is not trivial. Silo installations have specific characteristics that constrain the technology platform:
- Frequently remote locations with no fixed network infrastructure.
- Demanding environmental conditions: dust, humidity, wide temperature ranges.
- Low power consumption requirements when operating from limited or battery power.
- Reliable, secure communication with the central management system.
- Flexibility to integrate different sensor types (4–20 mA analogue, Modbus RTU, IO-Link).
The Wago PFC200 (reference 750-8202 for dual Ethernet, or 750-8204 with integrated 4G module) meets all of these requirements. It is a compact controller running embedded Linux with a native Codesys 3.5 runtime and accepts the full Wago 750-series I/O module range to connect virtually any sensor or actuator. Its operating temperature range (–20 °C to +60 °C) covers most outdoor installations or unheated industrial buildings.
Codesys 3.5 as the programming environment offers several key advantages: it is a well-documented IEC 61131-3 standard, natively supports the main industrial protocols (Modbus Master/Slave, MQTT, OPC-UA Server) and lets you structure the project in reusable function blocks that simplify maintenance and scaling when new silos are added to the network.
System architecture
A well-designed silo telemetry system has four layers: instrumentation, local control, communication and remote supervision. Here is each layer in detail.
Layer 1 — Instrumentation
Data quality starts with selecting the right sensor for the material stored:
| Variable | Typical technology | Output | Material / application |
|---|---|---|---|
| Radar level | Guided-wave or free-space radar | 4–20 mA / Modbus | Granules, powders, grain, cement |
| Ultrasonic level | Ultrasonic transducer | 4–20 mA | Liquids, light granules |
| Weighing / load cells | Load cells + transmitter | 4–20 mA / RS-485 | Feed, plastics, fine chemicals |
| Temperature | PT100 / PT1000 | 4–20 mA | Grain, perishable products |
| Humidity | Capacitive sensor | 4–20 mA / RS-485 | Grain, flour, animal feed |
| Differential pressure | Differential transmitter | 4–20 mA | Liquids, pressurised silos |
Analogue sensors (4–20 mA) connect directly to Wago 750-series analogue input modules (e.g. 750-467 for PT100 or 750-459 for 4–20 mA). Modbus RTU sensors connect via RS-485 using Wago serial communication modules (750-653) and are read from Codesys using the Modbus Master function block from the CAA library.
Layer 2 — Local control (Wago PFC200)
The Wago PLC acts as a field data concentrator and pre-processor. Its role is not just to read sensors and forward raw data — it executes local control logic so the silo continues to operate correctly even when communication with the central server is temporarily lost:
- Local alarm management: activation of visual or audible signals on critical minimum or maximum level, independently of connectivity.
- Fill and discharge control: opening and closing of valves, gates or conveyors based on measured level and configured recipes.
- Data buffer: local storage of the last N readings in the PFC200 non-volatile memory, sent as a batch when communication is restored (store-and-forward mode).
- Sensor watchdog: detection of wire break (signal outside 4–20 mA range), short circuit and defective sensor alarm.
The Codesys 3.5 programme is structured in reusable function blocks: one FB_SiloChannel per physical silo, encapsulating sensor reading, conversion to engineering units (tonnes or metres), fill percentage calculation, alarm threshold management and data preparation for transmission. This allows scaling from 1 to N silos with the same code, changing only instance parameters.
Layer 3 — Communication
The communication layer is critical for remote installations. The most common options, in order of preference, are:
- Ethernet with VPN (preferred when fixed network is available): the PFC200 connects to the local plant network and establishes a VPN tunnel (OpenVPN or WireGuard) with the central server. Higher bandwidth, low latency and minimal operating cost.
- 4G / LTE with industrial router: for installations without fixed connectivity or in open fields. We use industrial routers with SIM cards (Teltonika RUT241, RUT956 or the Wago 750-8204 integrated 4G module) to establish the connection. VPN over 4G ensures channel security. Data costs are minimal: a typical silo transmits less than 50 MB per month.
- LoRaWAN or NB-IoT: for very remote locations where 4G coverage is poor and data volume is minimal (level and temperature once per hour). Requires a nearby LoRaWAN gateway or operator NB-IoT coverage.
The transport protocol we use in most Wago + Codesys projects is MQTT with a broker on the server (Mosquitto or HiveMQ Cloud). Codesys has included a native MQTT library since version 3.5.13, which publishes each silo's data to a structured topic (plant/silos/silo01/level) with QoS 1, ensuring no messages are lost even when the connection is unstable.
For installations requiring integration with MES or corporate ERP systems, we add an OPC-UA server on the PFC200 (also native in Codesys), which exposes all silo data as nodes accessible from the management system's OPC-UA client.
Layer 4 — Remote supervision
Data arrives at the central server where it is stored and visualised. The most common options depending on installation size:
- Web dashboard with Node-RED + InfluxDB + Grafana: an open-source solution ideal for mid-size installations. Node-RED subscribes to MQTT topics, persists data in InfluxDB and Grafana displays the history of levels, temperature and alerts. Running on a low-cost VPS, the total monthly operating cost is very low.
- N3uron with MQTT Broker module: a more robust platform with native support for MQTT, OPC-UA and Modbus. Allows creating web supervisory dashboards without additional programming, with commercial technical support.
- Industrial SCADA (Ignition, WinCC OA): for large installations with redundancy requirements, long-term historical data, ERP integration and multiple simultaneous users with different access levels.
In all cases, the system generates automatic notifications by email, SMS or mobile app when any silo crosses configured thresholds: minimum replenishment level, critical alarm level, temperature out of range or sensor failure. The logistics manager receives the alert before the problem affects production.
Key system features
A silo telemetry system with this architecture delivers the following operational capabilities:
- Real-time visualisation: current level of each silo in percentage, tonnes or metres. An overview of the entire installation from a single web panel, accessible from any device.
- Consumption history: level curve over time that calculates daily, weekly and monthly consumption per silo and projects the depletion date based on the current consumption rate.
- Multi-level alerts: replenishment threshold (order now), alarm threshold (production at risk) and critical threshold (imminent stop). Each threshold can have different recipients.
- Fill traceability: automatic logging of each fill event with date, time, volume added and supplier (if integrated with the goods-receipt system).
- Automatic reports: scheduled generation and delivery of inventory reports in PDF or CSV format for purchasing or production departments.
- Multi-site management: all company silos — across different plants or regions — visible from a single unified portal, with per-user and per-site permissions.
Industries and applications
This type of system has direct application across very different sectors that share the same need: knowing at all times how much material is in their silos without relying on manual inspection.
- Animal feed: farms with distributed feed silos. The feed supplier can monitor customer tanks and optimise delivery routes proactively.
- Grain and agri-food: cooperatives and grain stores that need to monitor temperature and humidity to prevent fermentation and pest damage.
- Cement and construction materials: plants with cement, lime or plaster silos feeding bagging or mixing lines.
- Chemicals and plastics: polymer granule, resin or additive silos feeding extruders or injection moulding machines.
- Biomass and biofuels: pellet, wood chip or biodiesel tanks with temperature and level monitoring requirements.
- Waste management: industrial or municipal waste containers where the fill level determines the collection schedule.
Advantages over closed proprietary solutions
The market offers turnkey silo telemetry solutions from specialised manufacturers. The main disadvantage of these systems is that they are closed platforms: hardware, software and data platform all belong to the vendor, who charges a monthly subscription for access and premium rates for any customisation or integration with external systems.
The architecture we propose — Wago + Codesys + MQTT + open dashboard — is completely transparent: the client owns the entire system, can change integrator at any time, integrate data into their ERP or MES without vendor dependency, and scale the installation by adding new silos without additional licence costs.
How we work at Bluemation
At Bluemation we design and implement custom silo telemetry systems end-to-end — from sensor selection and Wago PLC sizing to supervisory dashboard deployment and client team training. Our workflow includes:
- On-site technical visit to define the instrumentation required based on material type and silo geometry.
- Communication architecture design based on available coverage and infrastructure.
- Codesys logic programming and data server configuration.
- Commissioning, sensor calibration and alarm threshold adjustment with the client's team.
- Remote support and system maintenance.
If you have industrial silos that you currently manage manually or with outdated systems and you want to know exactly what you have and when you need to reorder, tell us about your installation. We provide a no-obligation technical analysis and quotation.