Concepts

Understand the key building blocks before working with the application.

Workspace §

A workspace represents a single serial port connection. It groups all the Modbus RTU modules that are physically wired to the same RS485 bus.

Each workspace holds its own configuration: the serial port path (e.g., /dev/ttyUSB0 or COM3) and the polling interval. The baud rate is fixed at 9600 8N1 to match the iCTRL-20. When you connect a module inside a workspace, the workspace opens the serial port and starts sending Modbus read requests on a loop.

You can have multiple workspaces — one per serial adapter, for example — each running independently.

Module §

A module is an instance of a physical Modbus RTU device placed inside a workspace. Each module has:

• A name — the label you give it (e.g., "Pump Room Controller")
• A slave ID — the Modbus address of the physical hardware (one of 8 fixed values: 1, 2, 3, 4, 23, 34, 24, 234), set via its DIP switches
• A template — the module type that defines its I/O layout (DI count, AI count, etc.)

Multiple modules can exist in one workspace as long as each has a unique slave ID on the bus.

Module Sections §

Each module exposes its I/O organized into typed sections. A section is a logical grouping of related signals — for example, all digital inputs, or all analog outputs.

• DI
  Digital Input

  On/off signals from switches, sensors, or contacts. Supports pulse counting and DI-to-DO interlocking.

• DO
  Digital Output

  Relay or transistor outputs you can toggle on or off. Supports on-delay and off-delay timers.

• AI
  Analog Input

  Voltage (0–10 V) or current (4–20 mA) readings. Configurable min/max alarm thresholds.

• AO
  Analog Output

  0–10 V drive signals you can set to a specific value from the detail panel.

• PWR
  Power Supply

  Reports power supply state and alarm. Blurs AO controls when power failure is active.

• DEV
  Device Info

  Read-only: slave ID confirmed from hardware, serial number, and device status register.

See Module Sections for a full reference on each type.

Modbus RTU §

Modbus RTU is a serial communication protocol commonly used in industrial automation. It operates on a master/slave model where DZVOLT UI acts as the master, and each iCTRL-20 module is a slave identified by one of 8 fixed addresses (1, 2, 3, 4, 23, 34, 24, 234) set via hardware DIP switches.

The master sends read or write requests to a specific slave over the RS485 bus. DZVOLT UI polls each module's registers on a configurable interval and broadcasts the results to all connected browsers in real time.

Two register types matter:

• Coils — single-bit read/write values, used for digital outputs
• Holding registers — 16-bit read/write values, used for analog outputs and configuration

User Roles §

DZVOLT UI has two roles: Administrator and Operator. The difference is enforced on both the server and the UI.