Alfatech Modbus Configurator

Overview

The Alfatech Modbus Configurator is a mobile app that lets technicians and dealers set up elevator

controllers directly from a phone. It replaces manual, on-panel configuration with a guided interface that

reads and writes the controller's settings over the Modbus RTU protocol, and it adds secure, offline licensing

so the manufacturer stays in control of who can configure a lift and for how long.

How It Worked Before

Previously, the manufacturer configured the entire controller board at the factory before dispatch. If anything

needed to change on site — a floor count, a door delay, a display setting — a technician had to physically

connect to the board over USB with the manufacturer's tooling. Once a board was installed, the manufacturer

had no practical way to enforce payment: if the board was not paid for, there was nothing they could do from

a distance.

The Problem

• Factory-only configuration. Every board had to be fully set up by the manufacturer, and any later

change meant a USB connection and a site visit.

• No leverage on unpaid boards. After installation, the manufacturer could not stop or restrict a lift whose

board had not been paid for.

• No control over access. Nothing limited who could change settings, or for how long.

• No connectivity on site. Machine rooms and shafts often have no mobile data, so server-based licensing

is impractical.

• Diverse field teams. Many technicians are more comfortable in Hindi than in English.

Our Solution

A single Flutter application, shipped as two builds — a Master app for the manufacturer and a Dealer app for

distributors — that connects to the controller, authenticates with the device password, and presents every

setting as a clear form. All Modbus logic (frame building, CRC-16 checks, polling, response parsing) sits

above one transport boundary, so new connection types plug in without touching the rest of the app.

Key Capabilities

1. Full controller configuration

Reads the controller's registers into an editable dashboard and writes changes back. Covers floor setup, door

and timing settings, halt mode (Stop, Slow or Random Call), display segments, fire and welcome floors,

volume and more. Each write is confirmed by polling the controller until it acknowledges.

2. Offline authentication

Access is granted by a cryptographically signed activation key. The key carries the company, dealer ID,

dealer name, a unique key ID and an expiry time. The app verifies the signature locally — no internet, no

server call — so it works in a basement machine room. Master and Dealer builds use separate signing keys,

so a dealer key cannot unlock the manufacturer app.

3. QR code generation and scanning

Activation keys are issued as high error-correction QR codes that can be shared over WhatsApp, email or

any messaging app. The receiving technician scans the code with the camera or imports a screenshot from

the gallery; no long key needs to be typed.

4. Limited validity

Every key is time-bound. The issuer picks a window — 30 minutes, 1 day, 2 days or long-term — and the app

checks the expiry on every launch, locking configuration once it lapses.

5. Stop date for unpaid boards

The manufacturer (Master) and the dealer can each set a stop date that is stored on the controller itself. The

controller keeps track of it with no connection needed. Once that date passes, the lift goes into the configured

halt mode: Stop, Slow or Random Call. When payment is received, the controller shows an error code. The

issuer turns it into a short 12-character code tied to that specific unit and a new date. The technician enters

this code to release the lift or extend the date, with no USB and no factory visit.

6. Multilingual interface

The full interface is available in English and Hindi. Users choose a language on first launch or switch from

the home screen at any time; the choice is remembered across sessions.

7. Diagnostics and testing

A live diagnostic screen polls the controller once per second and shows status bits and error states, and a

testing-calls function lets a technician exercise the lift from the phone during commissioning.

From WiFi to Bluetooth

The first versions connected through a WiFi module on the controller: the phone opened a TCP connection

(Telnet port 23) and sent raw Modbus RTU frames. This worked, but required the WiFi module and a stable

network on site. In mid-2026 we added Bluetooth Low Energy support for the low-cost HM-10 module on

Android, so a technician can now connect with no network at all.

Users pick WiFi or Bluetooth from the dashboard; everything after connection — password, configuration,

diagnostics — works identically on both.

Development Timeline

Outcome

The configurator replaces factory-only setup and USB changes with a guided mobile workflow. Controllers

are configured on site in minutes, unpaid boards can be halted and released through a stored stop date,

access is limited to authorised people for a set period, licensing works without internet, and technicians can

connect over WiFi or Bluetooth in their preferred language.