Saia S-Bus ⇄ Modbus gateway

Need to connect Saia S-Bus and Modbus? The Weble WBox routes Saia S-Bus Modbus natively: one gateway speaks both protocols and maps data points in real time — no PC, no middleware, no cloud dependency.

The protocols

Saia S-Bus

Ether S-Bus is the native protocol of Saia-Burgess PCD controllers (SBC), widespread in Swiss buildings — reading and writing registers, flags, inputs and outputs.

Saia S-Bus driver →

Modbus

Modbus (TCP/IP and RTU) connects PLCs, meters, variable-speed drives and countless industrial devices.

Modbus driver →

Typical use case

A Saia PCD plant must exchange data with Modbus equipment — a third-party SCADA, frequency drives, a bank of energy meters. The WBox translates between the two worlds: S-Bus registers and flags appear as Modbus registers and coils, so the SCADA polls the legacy controllers without any change to the PG5 programs.

Example deployment

Typical scenario S-Bus ⇄ Modbus bridge for SCADA An industrial SCADA only speaks Modbus TCP. The WBox maps Saia PCD registers (Ether S-Bus over UDP) to Modbus registers, converting datatypes and scaling on the fly — the PCDs join the SCADA without reprogramming. Technical documentation →

How the WBox bridges Saia S-Bus and Modbus

On one side the WBox is an Ether-S-Bus master, reading and writing PCD registers and flags over UDP 5050. On the other it serves or polls Modbus — RTU on RS-485 or TCP on Ethernet, as master or slave depending on your architecture. Each S-Bus point is mapped to a holding register or coil, with type conversion and scaling on the gateway. Bidirectional: SCADA writes land in the PCD, PCD states surface in the SCADA.

Capacity & limits

Saia S-Bus — Ether S-Bus runs over UDP/IP — one connection per Saia PCD (station 0–255), reading and writing registers, flags, inputs and outputs; address lists import directly from PG5.
Modbus — Modbus addresses up to 247 slaves per line (RTU or TCP) — about 32 RTU devices per RS-485 segment before a repeater.

On the WBox, a driver licence enables the whole protocol — there is no artificial per-point tier to unlock. Capacity scales with the gateway model, from the compact S103 to the E413: you are bounded by the field bus, not by your licence.

Frequently asked questions

How do I connect Saia S-Bus and Modbus?

Saia S-Bus is the Saia PCD controller protocol (Ether S-Bus) and Modbus is the industrial register-based protocol. A single WBox gateway runs the Saia S-Bus and Modbus drivers, speaks both protocols at once and maps the data points between them — no PC, no middleware, no cloud dependency.