8 Channel RS485 MODBUS RTU relay board type R421A08


R421A08 8 channel Modbus relay module equipped with mature and stable 8-bit MCU and RS485 level communication chip,adopt standard MODBUS RTU format RS485 communication protocol. It can realize 8bit input signal detection and 8bit relay output. It can be used for digital detection or power control occasions.
  1>.Item name: 8CH Modbus Relay Module 
  2>.Work voltage:DC 12V
  3>.Baud rate:9600bps
  4>.Set address:0x01~0x3F
  5>.Delay time: 0~255s 
  6>.Load: AC 250V 10A or DC 28V 10A
  7>.Protocol:Modbus RTU
  8>.Interface:RS485/TTL UART
  9>.Control channel: 8channel
  10>.Operating Temperature:-20℃~85℃
  11>.Operating Humidity:5%~95%RH
  12>.Module Size:90*62*19mm

  • DC 12V power supply (voltage range 9-13V )
  • Standby current (all relays closed) 12MA, 1 relay open 40MA, 2 relays open 67MA, 3 relays open 95MA,4 relays open 121MA,5 relays open 147MA,6 relays open 173MA, 7 relays open 198MA,8 relays open 223MA
  • ''open'' ''close'' ''Momentary'' ''Self-locking'' ''Interlock'' ''Delay'' 6 Commands
  • MODBUS RTU command
  • Under the ''Delay'' command ,the maximum delay is 255 seconds
  • MODBUS commands can be made serial HyperTerminal (serial assistant) OR ''Modbus Poll'' Enter.
  • Under the MODBUS command mode, it can support up to 64 devices in parallel
  • Size: 90mm * 63mm * 20mm
  • Weight: 116 g
  • Maximum load: 10A / 250VAC, 10A / 125VAC, 10A / 30VDC, 10A / 28VDC, 10A / 12VDC


Automated industry PLC

Smart Home, Home Automation ,Wiser Home;

PTC Camera

Security Monitoring

Identification system;

Motor FW & BW


Typical applications:

MODBUS RTU command mode (HEX), you can control a variety of ways: Serial Hyper Terminal Control (need to manually add the CRC), Modbus Poll software control (software automatically add the CRC), PLC or MCU process control


  • Support Modbus RTU protocol
  • Support RS485/TTL UART interface
  • Output indicator in multi mode
  • Address can be set
  • Support input reverse connection protection
  • Relay switch output
  • Support parameter memory function

Kit include:

1 x DC 12V 8Ch RS485 Modbus RTU Relay Board

25 JD
In stock

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