Controller Communication Guide
One controller, many ways to connect. Each mode is explained simply, with guidance on when to use it.
The Controller connects wirelessly to the Growbud cloud. It also connects over wire to building systems and industrial sensors. It can read nearby Growbud sensors directly. This guide explains each mode in plain language, with a simple rule for when to use it.
Quick Pick
Just want it to work?
Use LoRaWAN with a Growbud gateway. This is the standard setup.
No gateway?
Connect from your phone over Bluetooth, and the Controller keeps running its on-board schedules offline.
Have wired Modbus devices?
Use Modbus master mode. The Controller polls sensors and commands actuators on the same bus.
Building management system runs the show?
Use Modbus slave or BACnet mode. Your BMS takes control.
Actuators or an industrial CAN network?
Use CANopen mode: master to drive actuators, or slave on an existing network.
On an IP network?
Use any Ethernet-to-RS485 Modbus adapter (see the Modbus slave section).
Run Home Assistant?
Use the Growbud Controller integration over Modbus. No app, cloud, or Edge at runtime.
Growbud soil sensors nearby?
Controller reads them automatically over Bluetooth. No extra setup.
LoRaWAN, the Standard Mode
LoRaWAN is long-range wireless. Controller talks to a Growbud gateway from miles away, with no wiring. One gateway can cover a large facility or an entire field.
Readings go up to the cloud. Commands, schedules, and configuration come down to the controller. Controller supports low-latency modes (Class B and C), so commands arrive in seconds, not minutes.
Fig. 1 · LoRaWAN
── wired - - wireless
When to use this
This is the default. If you have a Growbud gateway, use LoRaWAN.
Bluetooth for Setup and Service
Bluetooth is a direct connection from your phone or tablet to the controller. Stand near the Controller, open the app, and connect.
It handles the big jobs long-range wireless can't: full configuration pushes and firmware updates. Firmware updates are Bluetooth-only.
Fig. 2 · Bluetooth
── wired - - wireless
When to use this
Initial setup, on-site changes, and firmware updates.
Modbus Master: Controller Runs Your Wired Devices
If it speaks Modbus RTU, the Controller can run it. Wire it to the two-wire RS-485 port and the Controller polls sensors for readings and commands actuators to position, on the same bus, in the same scan. Readings land alongside your Growbud sensor data and the outputs join your rules and schedules.
One Controller acts as Modbus master for up to 128 devices on that bus, in any mix. On the sensing side: soil probes, EC and pH, flow meters, leak ropes, and energy meters. On the driving side: linear actuators for vents and dampers, valve and damper drives, VFDs, relay and I/O modules, and dosing pumps. Device count is not what you pay for, so instrument and actuate the room at the density it actually takes.
Setup is guided in the app:
- Pick a device preset, or define registers manually
- Set the device's address
- Run a live test read, or a test move, to confirm it works
- Link the readings and outputs to your zones
Fig. 3 · Modbus master
── wired - - wireless
When to use this
You already own wired industrial gear, sensors or actuators, and want it in Growbud dashboards, rules, and schedules. A large library of device profiles ships built in; email support@growbud.io with a model we are missing and we can usually add it in days.
Modbus Slave: Your Building System Controls Controller
This mode flips the same RS-485 port around. Your building-management system (BMS) becomes the master, and Controller joins the bus as a standard Modbus device.
The BMS can read Controller's status (per-channel state, faults, levels, currents) and command outputs through standard registers.
This is the same two-wire RS-485 serial bus BMS integrators already run, with a configurable device address.
Safety first: every command still passes through Controller's built-in safety interlocks. The BMS can't bypass leak shutoffs or hardware protections.
Connecting over Ethernet with RS-485 adapters
Controller's wired port is two-wire RS-485 (Modbus RTU). Many building systems and SCADA tools live on the IP network and speak Modbus TCP instead. A small, inexpensive Ethernet-to-RS485 Modbus gateway bridges the two, so your network sees Controller like any other Modbus TCP device.
- Wire the adapter's RS-485 terminals (A/B, plus ground if provided) to Controller's RS-485 port.
- In the Growbud app, open the Controller's Communication Settings and set the wired mode to Modbus Slave. Give Controller a device address (1–247) and note the serial settings (baud rate, parity, stop bits), these are configurable in the same screen.
- On the adapter's own setup page, configure it as a Modbus TCP-to-RTU gateway and set its serial side to match Controller's settings exactly (same baud, parity, stop bits).
- From your BMS or SCADA, connect to the adapter's IP address (standard Modbus TCP port 502) and use Controller's device address as the Modbus unit ID. Read status registers and write control registers as usual.
Every command still passes through Controller's built-in safety interlocks, no matter where it came from. The same adapter approach works for BACnet buildings via BACnet/IP-to-MS/TP routers when Controller is in BACnet mode.
Growbud doesn't make the adapter. Any standard Modbus TCP/RTU gateway works.
Fig. 4 · Modbus slave
── wired - - wireless
When to use this
Your facility's central control system should own irrigation decisions.
CANopen: Actuators and Industrial Control
The same wired port also speaks CAN bus. In CANopen mode the Controller runs as either side of the network: as a master, commanding CANopen actuators, drives, and remote I/O directly, or as a slave, joining an existing industrial network as a device the plant controller commands.
Pins 4 and 5 carry CAN_H and CAN_L on the industrial-standard pinout, so off-the-shelf CAN cordsets wire straight in, and pin 2 supplies up to 2 A of fused sensor power so a bus device can run from the same cable. Terminate with 120 Ω at both ends of the bus, the same fit-at-end jumper as RS-485.
Fig. 5 · CANopen
── wired - - wireless
When to use this
You are driving industrial actuators or valves that speak CANopen, or the Controller needs to join a plant network as a CANopen device.
Home Assistant
A Growbud Controller integration for Home Assistant talks to the Controller as a Modbus device and exposes each channel as a native entity: valves, switches, lights, fans, and levels you can put straight into Home Assistant automations. It also reads the Dro and Vero sensors paired to the Controller. Nothing from Growbud runs at runtime: no app, no cloud, no Edge.
The RS-485 to Ethernet adapter plugs straight into the same LAN as your Home Assistant box. No Growbud app or account is needed anywhere in the setup, and a button-press factory reset puts the Controller back into its default Modbus state whenever you want to start a direct Home Assistant setup. Email support@growbud.io for the integration package and install notes.
Fig. 6 · Home Assistant
── wired - - wireless
When to use this
Home Assistant already runs your site and you want the Controller's zones and sensors as entities in it, without adding a Growbud account.
BACnet MS/TP for BACnet Buildings
Some buildings standardize on BACnet instead of Modbus. Controller supports that too. It joins the BACnet MS/TP network as a device and exposes its channels and telemetry as BACnet objects your building automation system can read and write.
Same wiring (RS-485). Same safety interlocks.
One port, one mode: the wired modes, Modbus master, Modbus slave, BACnet, and CANopen share the one RS-485 / CAN port. Pick one at a time in the app's communication settings.
Fig. 7 · BACnet MS/TP
── wired - - wireless
When to use this
BACnet-based building automation.
Direct Sensor Monitoring: Controller Listens to Your Soil Sensors
Nearby Growbud Dro and Vero sensors broadcast their readings over Bluetooth. A linked Controller picks them up passively, no pairing dance, no connection per reading. Just link them and go.
Linked sensors automatically speed up to a fresh reading every minute. And they let Controller deliver their data to the cloud instead of using their own long-range radio, which saves sensor battery.
Failsafe built in: if the Controller goes offline or loses its cloud connection, sensors automatically switch back to their own radio within minutes. Data is never lost.
Fig. 8 · Direct sensors
── wired - - wireless
When to use this
It's automatic whenever Growbud sensors are in Bluetooth range of a linked Controller. This is how VWC-based irrigation automation gets minute-fresh data.
Ready to connect your Controller?
Shop controllers, sensors, and gateways, or schedule a demo to see how Growbud can help your operation.
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