Data Object Properties

  • MODBUS RTU packets are only intended to send data; they do not have the capability to send parameters
  • If the ability to send such parameters is needed, one should investigate a BACnet, EtherNet/IP, or other modern protocol
Name Type Access Visual
Discrete Input single bit read-only
Discrete Output (Coils) single bit read-write
Input Registers 16-bit word read-only
Holding Registers (Registers) 16-bit word read-write


  • Standard MODBUS RTU node addresses are 1-254, with 0 being reserved for broadcast messages and write only
  • The ‘0’ address is rarely used due to the fact that there is no confirmation that the message was properly received at the server node