Produits / TPMS
Modbus RTU TPMS: a slave node your PLC polls
The receiver answers reads; it never starts them. If your integration assumes a Modbus master on the tyre side, that assumption has to change before the purchase order, not after the first commissioning day.
Slave only — stated first because it decides the architecture
Our receiver works as a Modbus RTU slave only. Your PLC or SCADA is the master: it decides when to read and at what interval, and the receiver answers. It does not poll other devices, it does not initiate traffic, and it cannot be configured to take the master role.
That is not a limitation we are apologising for — it is the correct arrangement for a sensor node on a control network, because the control logic should own the timing.
Physical layer
- RS485 for a multidrop segment, or RS232 for a point-to-point link, depending on the interface fitted at the factory.
- One interface per unit — a receiver built with Modbus RTU is not also a CAN receiver.
- Up to 256 wheel positions per receiver, so a whole machine fits on one node.
- 10 ms data period at the receiver. Anything faster than that on the bus would be reading the same value twice.
What to send us before the unit ships
Baud rate, parity, stop bits and the slave address your master expects. These are set for the project, and setting them at the factory is cheaper than discovering a mismatch on site. If your network already has an addressing plan, send it — we would rather fit into it than hand you a device with a number you have to change.
Register map and scaling
The register map and the pressure/temperature scaling come with the unit in the integration note, and they match the configuration that was built. We deliberately do not publish a single "universal" table on this page: a table that is almost right is worse than no table, because it gets coded into a PLC program before anyone checks it.
What the receiver offers
| Parameter | Value |
|---|---|
| Wheel positions | up to 256 per receiver |
| Interface | one of: CAN · RS232 · RS485 · Modbus RTU — chosen at the factory, one per unit |
| Data period | 10 ms (receiver-to-bus refresh) |
| CAN bitrate | 250 kbps, software configurable |
| Supply | 10–30 V DC |
| Receiver protection | IP68 |
| Pressure accuracy | ±7 kPa |
| Temperature accuracy | 1 °C (error ≤ ±3 °C) |
Polling interval — a practical note
The receiver refreshes at 10 ms; the sensor radio interval is measured in seconds, not milliseconds. So a scan cycle of 100 ms, 0.5 s or 1 s all give you the same information — you are not losing data by polling slowly, and polling every 10 ms buys nothing but bus load. Pick the interval your control loop actually needs.
Questions we are asked
Can it be a Modbus master?
No. Slave only. If you need a master on the tyre segment, use a gateway or your own controller.
Which registers carry pressure and temperature?
They are in the integration note supplied with the unit, per interface. Ask for it with the quotation so your programmer has it before the machine arrives.
Does one node cover the whole machine?
Up to 256 wheel positions — yes for machine sizes we see in heavy plant, mining and lifting equipment. Radio path and repeaters decide the rest.
Send your bus settings
Tell us the master you use, the baud rate and the slave address you want, plus the wheel count. We will confirm the configuration and send the register map with the quotation. Receiver and sensor range · All configurations · Back to PLC integration
Tell us the application
Send the vehicle, wheel count and where the data must end up. We answer in writing.