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Product description: 8-channel relay module with opto-isolation - contacts 10 A / 250 V AC / 30 V DC - coil 7 V - 36 V - Modbus RS485 - Waveshare 25739
The Waveshare brand module allows you to control eight relays with a maximum load of 10 A 25 0V AC / 30 V DC . It works with automation systems, intelligent buildings, machine control or IoT systems. The configurable device address (1-255) allows you to cascade multiple devices on one RS485 bus . Thanks to built-in protective systems, such as power isolation, surge protection and interference filtering , the module ensures reliable operation in difficult industrial conditions. The module's terminals are screw connectors, and the whole thing is enclosed in an ABS housing with the possibility of mounting on a DIN rail.
Relay module 8 channels with optocoupler - contacts 10 A / 250 V AC / 30 V DC - coil 7 V - 36 V - Modbus RS485 - Waveshare 25739.
The relay module is easy to mount on a 35 mm DIN rail.
Main features of the relay module
- 8 Relay Channels : Supports up to 8 relays with a load of up to 10 A
- RS485 interface : uses the Modbus RTU protocol for communication, allowing multiple devices to be connected on a single bus
- Multi-level protection : protection against overvoltages, electrostatic discharge overvoltages, overcurrent protection
- Opto-isolation of relays : each relay has its own optical isolation, which protects it from the influence of high external voltages
- Easy to install : DIN rail housing allows easy installation in control cabinets
- Power Supply : Supports wide range of supply voltage from 7V to 36V
- Device addressability : the ability to configure the device address from 1 to 255, which facilitates the integration of multiple modules in complex industrial automation systems
- "Flash-on, flash-off" function : allows relays to be switched on for a short time and then automatically switched off via command
- LED Indicators : 3 LEDs to indicate MCU status and signal transmission status
Connecting the module to 220 V AC devices
- Connect power to the relay module (7 V to 36 V DC).
- Use terminals L (live) and N (neutral) to connect to a 220V AC power supply.
- Connect the device's power cable to the COM terminal and the NO terminal on the module to enable control of the device.
Connecting the module to 30 V DC devices
- Connect power to the relay module (7 V to 36 V DC).
- Connect the positive terminal of the device's power supply to the NO terminal and the negative terminal to the COM terminal.
- Make sure the power supply for the module and device meets the voltage requirements.
When connecting multiple modules in the system, ensure correct configuration of device addresses (1-255) and the possible use of RS485 repeaters to maintain stable communication over longer distances.
Module connection diagram.
Relay module controlled via RS485 bus, using the Modbus RTU protocol.
Communication and control
The module communicates via the Modbus RTU protocol via the RS485 interface. It supports multiple transmission speeds and the ability to address from 1 to 255 devices on one bus.
You can use Modbus RTU commands to control the module, e.g.:
- 01 05 00 00 FF 00 8C 3A - Relay 1 on
- 01 05 00 00 00 00 CD CA - Relay 1 Off
- 01 01 00 00 00 08 3D CC - Reading the status of all relays
The module can be operated using popular tools such as Modbus Poll, Arduino ID E and dedicated libraries for Raspberry Pi and STM32 .
Module Applications
- Industrial automation systems
- Controlling household appliances
- Lighting control
- Electric motor management
- Advanced monitoring and building automation systems
Relay Module Specifications
- Coil supply voltage: 7 V to 36 V
- Communication interface: RS485
- Baud rate: 4800, 9600, 19200, 3840, 57600, 128000, 256000
- Default communication format: 9600, N, 8, 1
- Number of relays: 8
- Connectors: 1NO 1NC
- Communication protocol: standard Modbus RTU protocol
- RS485 Address: 1 to 255
- Maximum relay load: 10 A 250 V AC / 30 V DC
- Protections: Power Isolation, Optical Isolation, Magnetic Isolation, Resettable Fuse and TVS, Surge Protection, Protection Diodes
- LED indicator:
- STA: MCU indicator, flashes when MCU is working normally
- TXD: TX indicator, flashes when sending data
- RXD: RX indicator, flashes when receiving data
- Housing material: ABS
- Mounting: on a 35 mm DIN rail
- Operating temperature range: -40ºC to 85ºC
- Operating humidity range: 40% RH to 80% RH
- Dimensions: 145 x 90 x 40 mm
