About 300 milliseconds. That’s how long a command takes to cross a healthy Zigbee2MQTT network, and some commands take seconds. It is the number that settles a popular idea: put Zigbee2MQTT in the middle, add an AI agent on top, and you have a robot controller for the price of a USB stick.
We reviewed the project in October 2026: its source code, the delays its users have measured, and the prices of commercial machine monitors. Zigbee2MQTT works like a sensory nerve. It senses, and it switches slow things. Anything that has to move needs a different path. One industrial use still holds up, and it is a lot more modest than a robot.
What Zigbee2MQTT is today
Zigbee2MQTT is a free bridge (GPL-3.0 licence) between Zigbee devices and an MQTT broker, the lightweight messaging protocol sensors use to talk to each other. Version 2.14.2 shipped on October 1, 2026, on a monthly release cadence. The GitHub repository has 15,723 stars.
The project site claims 5,798 supported devices from 608 vendors. We counted the models in the device-converter code (the October 13, 2026 version) and found 4,717. The gap is rebranded products, which account for 495 mentions in the code.
The coordinator, the radio stick that forms the network, costs little. The comparison guides we read list about $20 for a USB stick like the ZBDongle-E, about $40 for the Ethernet-powered SLZB-06, and $49 for the Home Assistant Connect ZBT-2. Those prices are in dollars, mostly American, so check the Canadian price.
Why anything that moves stays off this network
On a healthy mesh, a command takes about 300 ms from button to light (GitHub discussion 6892). That’s fine for a lamp. The trouble is the tail. Users report delays of up to about 20 seconds, and commands that fail after a 10-second timeout (issue 9528, issue 1333).
A motion-control loop needs predictable answers in under 100 ms. A message that sometimes arrives twenty seconds late can’t be fixed with better tuning.
The device catalogue shows the same limit. We counted device types in the converter descriptions (approximate counts, by keyword):
| Device type | Count in the code |
|---|---|
| Relays and switches | 1,046 |
| Blinds, curtains, and covers | 363 |
| Thermostats | 238 |
| Energy meters | 184 |
| Valves | 143 |
| Water-leak sensors | 95 |
| Locks | 64 |
| Window pushers | 3 |
| ”Finger robots” (they press a button) | 2 |
| Servos, steppers, linear actuators | 0 |
The only motors are blind and curtain motors, plus those two mechanical fingers. The robot mowers and vacuums that Home Assistant can drive connect over Wi-Fi, the cloud, Bluetooth, or a local MQTT bridge (openHAB example, Mammotion example). A robot that moves takes its commands over a wire, an ESP32, or Wi-Fi. Zigbee can hand it context over MQTT, such as a room temperature or whether a door is open.
What the network does well
Open a valve, close a blind, cut a relay, read a temperature. Those are slow, discrete jobs. Sinopé, a Quebec manufacturer, has its WL4200 and WL4210 leak detectors and its Sedna water valves defined in the Zigbee2MQTT converters, with valve_switch and valve_position commands. That’s the right size of task for this radio.
| Situation | Zigbee | Better choice |
|---|---|---|
| Battery sensors, valves, relays, blinds inside a building | Good | Zigbee |
| A machine that moves (mower, vacuum, arm) | Poor | Wire, ESP32, or Wi-Fi, with Zigbee as context |
| An alarm whose job is to report a power failure | Poor: mains-powered routers die with the power | Cellular gateway with a battery |
| Sensors spread over kilometres, like sugar-bush tubing | Poor: range | LoRa, up to 15 km in rural areas according to one vendor |
| Inside a steel panel or box | Weak | See below |
| Near variable-frequency drives | Disputed | See below |
The cellular-gateway and LoRa claims each come from a single vendor page (BarnTalk, which cites 24 to 30 hours of battery, and Airicom). Treat them as orders of magnitude.
One development to watch: Zigbee 4.0 and its Suzi variant, which runs below 1 GHz for longer range and better penetration through concrete, were announced on November 18, 2025. Certification opened on September 2, 2026, and no consumer devices exist yet. Today’s 2.4 GHz coordinators will never speak Suzi (PR Newswire).
The agent layer is already free
Home Assistant, the open-source home-automation platform, ships official MCP integrations, both server and client, refined in its 2026.9 release (Yahoo Tech). MCP (Model Context Protocol) is the standard socket an AI agent uses to call tools. The community server, ha-mcp, has 5,069 stars and was updated on October 14, 2026.
No MCP server exists for Zigbee2MQTT itself. Generic MQTT MCP servers are plentiful, and none has more than 5 stars. A small local model, Gemma 3 4B, handled the tools poorly in tests published by XDA Developers.
So nobody can sell you this layer; you download it. What’s left to decide is what the model may switch on its own. Free reading, writes only on a person’s confirmation, and a log of every command make a sensible floor for a lock, a heater, or a pump.
The one credible industrial use: knowing when your machines run
Picture a fabrication shop with older machines that have no data output. A clamp-on current sensor, clipped around the power cable, tells you whether the machine is drawing current, which means whether it’s running. A log of those readings gives run and idle hours per shift.
The hardware exists. A three-phase Zigbee clamp meter of the PC321 type sold for US$16 to US$32 (a 2022 listing cited in a project thread). A published review measured a 0.7% energy error against a utility meter, with a report about every 45 seconds (SmartHomeScene). OWON markets the same meter to integrators with Zigbee2MQTT support (OWON). A 45-second report gives run time to the minute. It doesn’t count cycles.
Commercial monitors publish prices per machine per month:
| Option | Published price |
|---|---|
| Zigbee clamp sensor plus coordinator | US$16 to US$32 per machine, plus a coordinator at about $40 and a small computer (price not captured) |
| Entry-level platforms | About $50 to $100 per machine per month |
| SensFlo Lite | $99 per machine per month |
| Evocon | $219 per machine per month (€159 to €319 on another page) |
| Guidewheel | About $15,000 a year minimum |
Sources: SensFlo, Caddis Systems, Guidewheel. Prices are the vendors’ own, not converted to Canadian dollars.
For ten machines, the commercial monitors run $6,000 to $26,280 a year. Sensors and a coordinator for the same ten come to roughly $200 to $360, before the small computer, the electrician, and the setup time. The comparison sets hardware next to a subscription. It says nothing about what each subscription includes.
The potential market is large. The STIQ barometer counts 13,755 manufacturing establishments with employees in Quebec in 2022 (a single source). Two grant guides say the ESSOR program covers half of some digitization projects (Zenitech, Chip FM). The ceilings differ between sources, and we haven’t verified that a sensor project qualifies, so confirm with the program.
What stays open
2.4 GHz near variable-frequency drives. The sources contradict each other. On one side, an unshielded drive radiates broadband noise into the 2.4 GHz band, documented in NIST data on a gantry crane (Sage Axe, Vertex Networks), and a shop owner reports unreliable Zigbee near dust collectors and compressors (Reddit). On the other, a vendor writes that drive noise generally doesn’t affect that band, and that Zigbee’s spread spectrum resists narrow-band interference (Valtoris). That source sells hardware. No search settles it. A test on site will: a coordinator and a router plug beside the noisiest machine for a week, logging link quality and lost messages. Budget $60 to $100 in hardware.
Steel panels. One manufacturer’s guide says cast iron and aluminium enclosures block 100% of 2.4 GHz (Valtoris). The sensors wrap cables inside the cabinet, but the signal has to get out. Where to put the coordinator and a router is a site question.
The electrician. Does Quebec require a licensed electrician to fit clamp-on sensors inside a panel? We didn’t check. Ask one before anyone opens anything.
The takeaway: a cheap sensor network that’s honest about its limits beats a robot promised by a radio that was never built for one.
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FAQ
Can Zigbee2MQTT control a robot?
Not one that moves. A command takes about 300 ms on a healthy mesh and sometimes several seconds, and the Zigbee2MQTT code has no device class for a servo, a stepper motor, or a linear actuator. The motors it supports are blind and curtain motors. For motion, use a wire, an ESP32, or Wi-Fi.
How long does a Zigbee command take?
About 300 ms from button to light on a healthy mesh, according to project discussions on GitHub. Users also report delays of up to about 20 seconds, and commands that fail after a 10-second timeout.
What does machine run-time logging with Zigbee sensors cost?
Clamp-on current sensors sell for US$16 to US$32 per machine, a coordinator costs about $40, and you need a small computer whose price we did not capture. For ten machines, the sensors and coordinator come to roughly $200 to $360. Commercial monitors publish $50 to $219 per machine per month. Those figures are vendors’ own, unconverted, and leave out the electrician and the setup time.
Does installing clamp-on sensors in a panel need an electrician?
We did not check whether Quebec law requires one for clamp-on sensors. Ask a licensed electrician before anyone opens an electrical panel, whether or not the rule applies.