HomeMaster STR-3221-R1 — Smart Stair Lighting Module, 32 Steps

Tech Specs

Note: Outputs are not internally fused per channel. Use external overcurrent protection on the LED supply rails per applicable standards and installation requirements.

Installation, Environmental & Mechanical

Home Assistant / Modbus / Web Config Integration

The STR-3221-R1 supports flexible integration with:

• HomeMaster MicroPLC and MiniPLC controllers
• PLC and SCADA systems via Modbus RTU
• Home Assistant using ESPHome or Modbus integration
• Direct USB-C configuration using browser-based WebConfig tool

Configuration parameters are stored persistently in onboard flash and automatically restored at power-up.

Quick Setup Process (USB-C WebConfig)

1. Mount & Power - Mount the module on a DIN rail and connect 24 V DC.
2. Connect USB-C - Connect USB-C cable to the module.
3. Open WebConfig - Open WebConfig page in Chrome or Edge browser.
4. Connect Device - Click Connect and select the device.
5. Configure - Set Modbus address and baud rate.
6. Test I/O - Test outputs O1-O32, status LEDs and digital inputs.
7. Save & Disconnect - Save settings and disconnect USB-C.

Features:

• Driverless browser-based configuration
• Live configuration and diagnostics
• Persistent flash storage
• No external software required

WebConfig provides Modbus address, baud rate, I/O test, and channel configuration (stored persistently in flash).

uart:
  id: uart_modbus
  tx_pin: 17
  rx_pin: 16
  baud_rate: 115200
  parity: NONE
  stop_bits: 1

modbus:
  id: modbus_bus
  uart_id: uart_modbus

packages:
  str1:
    url: https://github.com/isystemsautomation/homemaster-dev
    ref: main
    files:
      - path: STR-3221-R1/Firmware/default_str_3221_r1_plc/default_str_3221_r1_plc.yaml
        vars:
          str_prefix: "STR#1"
          str_id: str_1
          str_address: 21
    refresh: 1d

Cabling and Wirings

Power Supply

Module power (V+ / 0V): The STR-3221-R1 logic and communication operate from 24 V DC SELV/PELV only. Connect +24 V and 0 V (GND) to the terminals marked V+ and 0V.

LED power (LED PS + / -): The LED supply terminals accept 12 V or 24 V DC. Use a separate supply for the LED loads; outputs are low-side switching and require a common LED supply rail to the VCC group pins.

Connect + to V+ and - to 0V.

Terminal Block Layout

Top blocks: V+ / 0V (24 V DC module supply), LED PS +/- (12 or 24 V DC LED supply), SENS.A / SENS.B (fused 24 V sensor rails), IN1 / IN2 / GND (digital inputs). Output blocks: O1-O32 low-side outputs grouped with shared VCC rails. Comms block: A, B, COM (RS-485 Modbus RTU).

Front view: power, sensor rails and inputs (top); 32 outputs and RS-485 (bottom).

Output Wiring (O1-O32)

Output channels are low-side MOSFET sinks (SI2307A). Connect the LED load + to the corresponding VCC group rail (12 or 24 V from the LED supply) and the load - to the channel terminal (O#). Built-in SS24 flyback diodes protect against inductive switching transients. Maximum 1 A per channel; total module load 3 A typical at 24 V DC.

Digital Input Wiring (IN1, IN2)

Inputs use ISO1212 galvanic isolation. Connect dry contacts or 24 V DC sourcing sensors only (IN1/IN2 with GND). Each input has PTC fuse, TVS, and reverse protection. Do not inject external voltage above 30 V DC.

Dry-contact wiring to IN1 and IN2 (common GND).

PIR motion sensors powered from SENS rail and signaling IN1/IN2.

RS-485 Wiring

Connect A and B to the bus; COM is optional common reference. Use twisted-pair (120 Ohm characteristic impedance); shielded cable recommended in industrial environments. Enable 120 Ohm termination only at the last device on the bus.

Connect A, B, and COM to the bus; 120 Ohm termination at line end.

Cable Recommendations & Shield Grounding

General Routing Rules

• Route low-level signal cables (RS-485, DI) separately from power and LED wiring.
• If crossing power cables is unavoidable, cross at 90°.
• Keep cable runs as short as practical; avoid parallel runs with high-current conductors.

RS-485 (Modbus) Cable

• Twisted pair recommended (120 Ohm characteristic impedance).
• Shielded cable recommended in industrial environments.
• Use one twisted pair for A/B; use second conductor as COM reference if required.
• Examples: J-Y(ST)Y 2×2×0.5 mm² or LI2YCY PiMF 2×2×0.50.

Shield Grounding

• Bond cable shield(s) to cabinet PE/EMC ground at one end (PLC side recommended).
• Do not connect shields directly to signal terminals (A/B/COM).

System Architecture & Pinout

System block diagram.

RP2350 MCU and terminal pinout.

Field board layout: 32 MOSFET outputs, ISO1212 inputs, 24 V DC power rails.

MCU board layout: RP2350, TLC59208F drivers, MAX485, USB-C.

Safety and Installation Notes

• Module logic: use only SELV/PELV 24 V DC on V+ / 0V. LED supply (+ / -) can be 12 or 24 V DC.
• Install inside a control cabinet; protect wiring terminals from accidental contact.
• Each module must have its own 24 V DC supply for V+ / 0V; do not bridge GND_FUSED and logic GND externally.
• Never connect mains voltage to any terminal - this is a SELV-only product.
• Size LED supply and wiring for up to 1 A per channel (3 A total typical); use appropriate fusing on the LED supply.
• Sensor rails (SENS.A / SENS.B) provide limited fused 24 V output - do not backfeed external power.
• Installation and servicing by qualified personnel only.

Compliance & Certifications

The STR-3221-R1 module is CE marked. ISYSTEMS AUTOMATION S.R.L. (HomeMaster® brand) maintains the technical documentation and a signed EU Declaration of Conformity (DoC) available for download in the Documentation section above.

• EMC Directive 2014/30/EU - EN 55032:2015 (Class B emissions), EN 55035:2017 (immunity), tested by Idvorsky Laboratories Ltd. (Job #1648)
• RoHS Directive 2011/65/EU - EN IEC 63000 technical documentation
• Low Voltage Directive 2014/35/EU - does not apply (SELV-only product, 24 V DC nominal, no mains-capable terminals)
• HomeMaster® - registered EU trademark (EUTM No. 019082911, EUIPO, registered 15 January 2025)