Industrial I/O Control, Redefined.
The iCTRL-20 is a modular, programmable industrial I/O controller with 20 I/O points, Modbus RTU communication, and autonomous operation — no PLC required.
Built for Industrial Reality
A complete control solution that works autonomously, speaks Modbus RTU over both RS-485 and USB-CDC, and scales across your RS-485 bus.
Autonomous Operation
Runs independently with built-in logic, timers, and alarms. No PLC or external controller required for standalone control loops.
Dual Modbus RTU
Industry-standard Modbus RTU slave on two interfaces simultaneously: RS-485 (UART1, up to 1200 m, 8 modules per bus, hardware-selectable ID) and USB-CDC (UART0) for direct PC access — with write-priority lockout when both are active.
12 Internal Functions
DI→DO linking, AI alarms with hysteresis, power-OK response, 4 timer modes (TON/TOF/TP/TONOFF), per-input analog scaling, logic inversion, AI→AO direct linking, DI pulse counters, NVS auto-save, and hardware safety interlock.
Safety Interlock
Hardware safety interlock input instantly disables all outputs. Combined with power status detection and 24h Li-ion battery backup.
Real-Time Processing
ESP32-S3 dual-core with a real-time OS. Deterministic multitasking with ≤10 ms internal I/O cycle. Analog sampling, logic, timers, and Modbus run in parallel.
Open Architecture
Vendor-agnostic by design. Full Modbus memory map and GPIO pin map are published — integrate with any SCADA / HMI / gateway, or drop in your own firmware. No lock-in.
Non-Volatile Storage
All configuration persists in flash memory across power cycles. Auto-save mode ensures zero data loss on unexpected shutdowns.
Industrial Grade
Stainless steel enclosure, DIN rail mount, IP20 protection, -10 to +60°C range, reverse polarity and transient protection, EN61131-2 zone B immunity.
Specifications
Engineered for reliability in demanding industrial environments.
12 Internal Functions
Configure advanced control logic directly on the module — no external programming required.
Analog Output Control
Set 0-10V analog output values via DZVOLT UI software or Modbus holding registers.
AI Alarm → DO
Set min/max thresholds on analog inputs. Trigger outputs when values exceed limits.
Power OK → DO
Link the power status to a designated digital output. DO activates when power is OK.
DI → DO Linking
Map any digital input directly to any digital output for instant pass-through control.
Timer Engine
4 modes per output: TON (on-delay), TOF (off-delay), TP (pulse), TONOFF (cyclic on/off).
0-10V Input Scaling
Convert raw voltage inputs to real engineering units with configurable min/max scaling.
4-20mA Input Scaling
Convert current loop inputs to real values — temperature, pressure, flow, level, etc.
DI Logic Inversion
Configure each digital input as normal or inverted logic via software.
NVS Auto-Save
Toggle coil 00005 to persist every holding-register and coil change to flash. Configuration survives power loss; disabling the coil clears NVS.
Safety Interlock
Hardware interlock input (read at discrete input 10014) instantly forces all outputs off, independent of the Modbus master. Fail-safe by design.
AI → AO Direct Linking
Pass any analog input straight to any analog output (registers 40078–40081). Loop sensor signals to actuators with no Modbus master in the loop.
DI Pulse Counters
Each digital input has a 16-bit rising-edge counter (0–65535) with a per-channel enable coil. Read counts at input registers 30011–30014.
Real-Time Processing Architecture
Modbus Register Map
Complete register-level access to all I/O, configuration, and diagnostics via standard Modbus RTU function codes.
| Type | Address | Parameter | Access |
|---|---|---|---|
| Coils | 00001 – 00004 | Digital Outputs DO1 – DO4 | R/W |
| Coils | 00005 | Auto-Save to Memory | R/W |
| Coils | 00006 – 00009 | DI Pulse Counter Enable (DI1 – DI4) | R/W |
| Discrete | 10001 | DI Power OK | R |
| Discrete | 10002 – 10005 | Digital Inputs DI1 – DI4 | R |
| Discrete | 10006 – 10013 | AI Threshold Alarms (AI1 – AI8) | R |
| Discrete | 10014 | Safety Interlock Status | R |
| Discrete | 10015 – 10018 | Raw State of DO1 – DO4 | R |
| Input Reg | 30001 | Slave ID (Device Address) | R |
| Input Reg | 30002 – 30009 | Analog Input Values (AI1 – AI8) | R |
| Input Reg | 30010 | Serial Number | R |
| Input Reg | 30011 – 30014 | DI Pulse Counters (DI1 – DI4, 0 – 65535) | R |
| Input Reg | 30015 – 30018 | AO Voltage Feedback (AO1 – AO4, ×100) | R |
| Holding | 40001 – 40004 | Analog Output Values (AO1 – AO4) | R/W |
| Holding | 40005 – 40008 | DI → DO Link Mapping | R/W |
| Holding | 40009 | DI Power OK → DO Link | R/W |
| Holding | 40010 – 40025 | AI Alarm Thresholds (Min/Max) | R/W |
| Holding | 40026 – 40033 | AI Alarm → DO Link Mapping | R/W |
| Holding | 40034 – 40053 | Timer Values (TON/TOF/TP/TONOFF) | R/W |
| Holding | 40054 – 40057 | Timer Mode Select (per DO) | R/W |
| Holding | 40058 – 40073 | AI Scaling (Min/Max per input) | R/W |
| Holding | 40074 – 40077 | DI Logic Inversion | R/W |
| Holding | 40078 – 40081 | AI → AO Direct Link Mapping | R/W |
Supports FC01, FC02, FC03, FC04, FC05, FC06, FC16 — 81 holding registers, 18 discrete inputs, 18 input registers, 9 coils. Data format: 8 data bits, no parity, 1 stop bit (8N1).
Documentation
Datasheet, user manual, register map, and certifications — everything you need to integrate iCTRL-20.
Datasheet
Electrical specifications, mechanical drawings, terminal layout, operating conditions, and ordering information.
User Manual
Installation, wiring, Modbus configuration, example use cases, and troubleshooting.
Memory Map
Complete Modbus address tables for coils, discrete inputs, input registers, and holding registers.
Wiring Diagram
Terminal pinout, connector reference, RS-485 bus topology, and DIN rail mounting.
Pin Mapping
GPIO-to-function map for DI, DO, AI, AO, RS-485, USB, and slave-ID selection pins.
Block Diagram
System architecture: ESP32-S3 core, I/O blocks, communication interfaces, and signal flow.
RoHS Declaration
Declaration of conformity for RoHS directive 2011/65/EU and amendments.
Built for Every Industry
From factory floors to agricultural fields, the iCTRL-20 adapts to your application.
Industrial Automation
Machine control, conveyor systems, packaging lines, and process interlocking.
SCADA & PCS Integration
Remote I/O expansion for existing SCADA systems via Modbus RTU.
Renewable Energy
Solar plant monitoring, hybrid energy systems, battery management, and grid telemetry.
Building Automation
HVAC control, lighting systems, access management, and energy monitoring.
Agriculture & Smart Farming
Irrigation control, pumping stations, greenhouse monitoring, and environmental sensing.
Data Acquisition
Multi-channel sensor logging, telemetry systems, and R&D measurement platforms.
IIoT & SCADA Integration
Modbus-native IIoT. Browser-based monitoring via DZVOLT UI; integrates with any SCADA, gateway, or cloud platform over Modbus RTU.
Education & Prototyping
Arduino-compatible platform for learning industrial control, PLC concepts, and Modbus communication.
Ready to Control
Your Next Project?
Whether you need 1 module or 100, we're ready to help you integrate the iCTRL-20 into your system.