TCP/IP M2M Controller C4

Internet of ThingsModbusRS422/RS485

PLATFORM OVERVIEW
The C4 series is an industrial IoT controller built around the Raspberry Pi Compute Module 4 in a housing for DIN-rail or wall mounting. Available sizes (4MU, 8MU, 12MU) fit standard switchboard front cutouts. Multiple variants offer combinations of RAM and configurable digital/analog I/Os suitable for building automation, industrial control and cloud-connected applications.

KEY PLATFORM FEATURES
Industrial enclosure for DIN-rail and wall mounting; wide-range power supply 12–48 Vdc; ARM co-processor for time-critical tasks and serial interface handling; persistent 2 kB ferromagnetic RAM; unique 96-bit serial number; real time clock with backup capacitor; status LEDs and DIP switch for software use. Standard Compute Module 4 interfaces available: 1x Micro HDMI, 1x Ethernet, 2x USB 2.0. RAM options: 2 / 4 / 8 GB; standard 32 GB SD card with Linux OS (configurable).

BUILT-IN INPUTS & OUTPUTS
Several variants integrate digital and analog I/Os. The ARM co-processor manages I/O internally so application software typically accesses I/Os via a serial device. The co-processor maps serial devices for native Linux access and performs RS485 direction switching.

• Serial devices: /dev/ttyACM0 (ASCII protocol), /dev/ttyACM1 (MODBUS/RTU master)
• RS485: exposed via USB (e.g. /dev/ttyACM2) and managed by the co-processor
• Optional relay outputs and special IOs (LED strip drivers, temperature sensor inputs, shade/blind control)

UNIVERSAL ANALOG INPUTS / OUTPUTS (AIOX)
AIOX modules are available in 4, 8 or 16 channel variants. Each channel is individually configurable as one of the following:

• 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: 0–1 MΩ
• Temperature sensor input: PT100, PT1000, NI1000 (DIN43760)
• Digital input: 24 Vdc or dry contact

DIGITAL I/Os
Digital inputs accept 12–48 Vdc signals. Digital outputs switch up to 30 Vdc and up to 750 mA per channel. All digital outputs include short-circuit and thermal overload protection. Integrated diagnostics (open wire, overcurrent, short to Vdd, etc.) enable monitoring and alarming of remote stations.

HOW TO USE THE SERIAL INTERFACE?
Use /dev/ttyACM0 for a simple ASCII text protocol and /dev/ttyACM1 for MODBUS/RTU master communications. The co-processor maps RS485 to a native serial device (e.g. /dev/ttyACM2) and handles time-critical direction switching, offloading this task from the Linux system.

SOFTWARE & ECOSYSTEM
Controllers ship with a standard Raspberry Pi Linux distribution and support common open-source tools and environments.

• Development: Node-RED, Node.js, Python, Java, JavaScript, C#, C++, Scratch
• Databases: MariaDB, MongoDB, InfluxDB, PostgreSQL
• Visualization / Web: Grafana, Apache
• Home automation: OpenHAB, FHEM, Home Assistant, ioBroker
• Cloud / Protocols: MQTT, HTTPS, Azure IoT, AWS
• VPN / Router: OpenWrt, OpenRouter, OpenVPN, WireGuard
• Industrial PLC: CODESYS

SELECT YOUR VERSION
Multiple variants are available combining RAM size and number/type of analog and digital I/Os. Not all combinations are possible; check product details or order codes for the selected configuration.

TECHNICAL SPECIFICATIONS

• Series: C4 IoT controller based on Raspberry Pi Compute Module 4
• Example reference: RESI-C4-A-4AIOX-2GB (varies by configuration)
• Enclosure: industrial housing for DIN-rail and wall mounting; sizes: 4MU, 8MU, 12MU
• Power supply: 12–48 Vdc wide-range
• Co-processor: ARM co-processor; unique 96-bit serial number; 2 kB ferromagnetic RAM; RTC with backup capacitor; status LEDs; DIP switch
• Compute Module 4 interfaces: 1x Micro HDMI, 1x Ethernet, 2x USB 2.0
• RAM options: 2 / 4 / 8 GB; storage: 32 GB SD card with Linux OS (standard)
• Analog IO (AIOX): 4 / 8 / 16 channels, configurable (0/2–10 V, 0/4–20 mA, 0–1 MΩ, PT100/PT1000/NI1000, digital)
• Digital inputs: 12–48 Vdc
• Digital outputs: up to 30 Vdc, up to 750 mA per channel; short-circuit and overload protected
• Diagnostics: open wire, overcurrent, short-to-Vdd detection
• Optional IO: relay outputs, LED strip drivers, special temperature sensor inputs, shade/blind control
• Serial interfaces: /dev/ttyACM0 (ASCII), /dev/ttyACM1 (MODBUS/RTU master), /dev/ttyACM2 (RS485 via USB)
• Note: no space for a built-in second Ethernet or LTE modem in these versions