Modbus - Libelium Waspmote Technical Manual

21.4. Modbus

The Modbus is a software library that can be operated physically on the RS-485 modules. Thus, Modbus is a
software layer which provides with interesting services.
Technical details:
Protocol: Modbus
•
Data area: Up to 255 bytes per job
•
Interface: Layer 7 of the ISO-OSI reference model
•
Connector: DB9 (RS-485 module)
•
Number of possible connections: up to 32 in multi point systems
•
Frame format: RTU
•
Applications:
Multiple master-slave applications
•
Sensors and Instruments
•
Industrial Networking
•
Building and infrastructure
•
Transportation and energy applications
•
Related API libraries:
Wasp485.h, Wasp485.cpp
•
ModbusMaster.h, ModbusMaster.cpp
•
ModbusSlave.h, ModbusSlave.cpp
•
All information about their programming and operation can be found in the
Modbus Communication
All the documentation is located in the Development section in the Libelium website.
Guide.
RS-485 Communication Guide
-114-
Industrial Protocols
Figure: RS-485 module
and
v8.2