TCP/IP M2M Controller C4

Internet of Thingscellular IoTRS422/RS485

Overview
The C4 is an industrial-grade IoT controller based on the Raspberry Pi® Compute Module 4, supplied in DIN-rail / wall-mount housings (4MU, 8MU, 12MU). It combines a CM4 application platform with an integrated ARM® co-processor and wide-range power input to meet industrial monitoring and control requirements.

What’s different?
Designed for switchboard integration with a 45 mm front cutout, the C4 adds a dedicated ARM® co-processor for time-critical I/O handling, a wide-range 12–48 Vdc power supply and modular I/O configurations for flexible industrial deployment.

ARM® co-processor — features

• Internal handling of RS485 and other time-critical interfaces
• Unique 96-bit serial number for device identification
• 2 kB ferromagnetic RAM for persistent small-data storage
• Real-time clock with backup capacitor
• Status LEDs and DIP switch for local configuration and diagnostics

Raspberry Pi Compute Module 4 — available features

• 1× Micro HDMI
• 1× Ethernet
• 2× USB 2.0
• RAM options: 2 GB, 4 GB, 8 GB
• 32 GB SD card with Linux OS (standard delivery)

Built-in inputs & outputs
Models are offered with integrated digital inputs and relay outputs. The ARM® co-processor maps and manages I/O so host applications access signals via simple serial interfaces for reliable industrial operation.

Digital / Relay IO details

• Digital inputs: designed for 12–48 Vdc signals
• Relay outputs: rated up to 30 Vdc or 250 Vac, max. 6 A per channel
• Relay contact material: AgSnO2
• Optional solid-state relays: 1 A (230 Vac/dc), 3 A (60 Vac/dc), 6 A (60 Vac/dc) for high cycle life

Universal analog inputs/outputs (AIOX)
Available in 4, 8 or 16 channels; each channel is individually configurable as:

• Analog input: 0 / 2–10 V or 0 / 4–20 mA
• Analog output: 0 / 2–10 V or 0 / 4–20 mA
• Resistor measurement input: 0 to 1 MΩ
• PT100, PT1000, NI1000-DIN43760 sensor input
• Digital input for 24 Vdc or dry contact

How to use the serial interfaces

• dev/ttyACM0 — simple ASCII text protocol for general I/O
• dev/ttyACM1 — MODBUS/RTU master protocol
• dev/ttyACM2 — RS485 mapped via USB (direction switching handled by the co-processor)

Software & integration

• Delivered with standard Raspberry Pi Linux distribution
• Supports common open-source stacks: Node-RED, NodeJs, Python, Java, C/C++, etc.
• Compatible with SQL/NoSQL databases: MariaDB, MongoDB, InfluxDB, PostgreSQL
• UI and visualization: Grafana, Apache; home automation: OpenHAB, Home Assistant, ioBroker
• Cloud connectivity: MQTT, HTTPS, Azure IoT, AWS
• VPN & routing: OpenWrt, OpenVPN, WireGuard
• Optional: multimedia (KODI), industrial PLC (CODESYS)

Available variants & add-ons

• Example IO configurations: 10xRI + 8xRO; 20xRI + 16xRO; 32xDI + 12xRO; 32xDI + 24xRO
• C4 add-ons: none; 2nd Ethernet; built-in LTE modem
• RAM sizes: 2 GB, 4 GB, 8 GB

Usage
Designed for remote-station monitoring, control and alarming, the C4 is suitable as an IoT PLC or DDC in building automation and industrial environments where modular I/O, serial access and CM4 application flexibility are required.

Technical specifications

• Series: C4 (Compute Module 4 based IoT controller)
• Housing sizes: 4MU, 8MU, 12MU (DIN-rail / wall mounting)
• Power supply: wide-range 12–48 Vdc (built-in)
• Co-processor: ARM® co-processor with 96-bit serial, 2 kB ferromagnetic RAM, RTC with backup capacitor, status LEDs, DIP switch
• Serial interfaces: dev/ttyACM0 (ASCII), dev/ttyACM1 (MODBUS/RTU master), dev/ttyACM2 (RS485 mapped via USB)
• Digital inputs: 12–48 Vdc
• Relay outputs: up to 30 Vdc / 250 Vac, max. 6 A per channel (AgSnO2 contacts)
• Solid state relay options: 1 A (230 Vac/dc), 3 A (60 Vac/dc), 6 A (60 Vac/dc)
• AIOX channels: 4 / 8 / 16, configurable per channel (0/2–10 V, 0/4–20 mA, resistor measurement 0–1 MΩ, PT100/PT1000/NI1000 inputs, digital input for 24 Vdc / dry contact)
• Compute Module 4 features: 1×Micro HDMI, 1×Ethernet, 2×USB 2.0, RAM options 2/4/8 GB, 32 GB SD card with Linux OS
• Typical IO configurations available: 10xRI+8xRO; 20xRI+16xRO; 32xDI+12xRO; 32xDI+24xRO
• Optional add-ons: 2nd Ethernet, LTE modem