Industrial Interfaces: RS-485, Modbus and CAN

10 Lektionen in dieser Stufe

1. Industrial Signal Levels: 24 V I/O, Isolation and Noise
   Explain why industrial wiring differs from bench wiring. · Lab: Compare 3.3 V and 24 V signalling on a long cable next to a switching motor.
2. Isolated Digital Inputs and Outputs
   Interface 24 V sensors and actuators through optocouplers and relays. · Lab: Read a 24 V proximity-style switch through an optocoupler and switch a 24 V lamp.
3. Reading 4-20 mA Current Loops and 0-10 V Signals
   Convert process signals into engineering units and detect a broken wire. · Lab: Read a 4-20 mA source through a receiver module and flag an open loop.
4. RS-485 Wiring, Termination and Biasing
   Build a differential bus that works over long distances. · Lab: Wire a three-node bus, then observe reflections with and without termination.
5. Modbus RTU as a Client with pymodbus
   Read and write coils and registers on serial devices. · Lab: Poll a Modbus sensor and switch a Modbus relay module from Python.
6. Modbus TCP and Serving Your Own Registers
   Expose your device's data to a controller over Ethernet. · Lab: Run a Modbus TCP server that publishes sensor values and accepts a setpoint.
7. CAN Bus Physical Layer and an MCP2515 HAT
   Bring up a CAN interface with correct bit rate and termination. · Lab: Enable the CAN overlay, wire two nodes and bring the interface up.
8. Sending and Filtering Frames with SocketCAN and python-can
   Exchange frames, apply filters and decode signals from a message definition. · Lab: Send periodic frames, filter by identifier and decode a packed value.
9. Surge, ESD and EMC Protection for Field Wiring
   Protect ports that leave the enclosure. · Lab: Add suppressor diodes, common-mode chokes and proper shielding to an RS-485 port design.
10. DIN-Rail Enclosures and 24 V Supply Design
    Package a Pi for a control cabinet with correct power and grounding. · Lab: Mount the gateway on a rail, power it from 24 V and label every terminal.

Abschlussprojekt

A DIN-rail gateway powered from 24 V that polls Modbus devices over RS-485, exchanges frames on a CAN bus, reads isolated inputs and publishes everything to MQTT.

Teile für diese Stufe

• 1 × Raspberry Pi 5, Pi 4 or Compute Module set from earlier levels
• 2 × Isolated RS-485 HAT or USB to RS-485 adapter
• 1 × RS-485 Modbus temperature and humidity sensor
• 1 × Modbus RTU relay module 4-channel
• 2 × MCP2515 CAN HAT with transceiver (isolated type preferred)
• 1 × Second Raspberry Pi or Pico as a CAN and Modbus peer
• 1 × 24 V DC DIN-rail power supply
• 1 × 24 V to 5 V isolated DC-DC converter
• 1 × Optocoupler input module 24 V to 3.3 V
• 1 × 4-20 mA current loop receiver module
• 1 × 4-20 mA signal generator or transmitter
• 1 × Twisted-pair cable and 120 ohm termination resistors
• 1 × DIN-rail enclosure for Raspberry Pi
• 1 × Screw terminal blocks and ferrules

In jeder Lektion legst du die passenden Teile direkt in den Warenkorb. Raspberry Pi →