uMODBUS Toolkit

December 3, 2018 Cypherbridge Systems LLC

The Cypherbridge uMODBUS Toolkit is a compact software library designed for small and medium memory models where resources are carefully allocated and balanced. The uMODBUS toolkit includes a fully integrated slave solution with RTU and TCP protocol support, along with a master application for system integration and test.


Modbus a serial communications protocol used in industrial control and SCADA supervisory systems. It interfaces master and slave devices over communications channels including Modbus RTU serial multipoint, and Modbus TCP over standard IP networks.

Modbus is widely deployed into applications include SCADA, industrial control, building control and security, and many more.

Modbus connects the master to multiple slave, or remote terminal unit (RTU) nodes. Data objects provided by slave devices can be single bit or 16-bit register, read-write or read-only.

Modbus communication protocol is master and slave, with each slave assigned a unique address. Data transfers are defined by master polling scheme. Message payloads include a CRC integrity check.


The uMODBUS Toolkit provides modbus slave interface to local resources such as sensors, actuators, and system data elements. The default slave address is configured at compile time or initialized from NV memory.

The modbus register database includes user registers, with a configurable secondary slave address register. The modbus slave will respond to the default and secondary slave address.

Platform implementations can provide a persistent register database that can be saved and recalled from NV memory across reset and power cycles.


The uMODBUS toolkit uses well-defined chip, board, RTOS and network porting interfaces. Tasks and timers can be implemented in a non-threaded or RTOS based design. The toolkit is delivered pre-built and tested on a standard target evaluation kit, and including the integrated platform kit, along with toolchain workspace project files.


uMODBUS is supported by a master application that can be used over TCP or RTU channels to develop and test the slave devices. Registers are configurable by build options in the project.


• Sample register database included with persisted save and recall

• Assignable secondary slave address

• Register access functions interface to sensors, actuators, and managed data.

• Portable ANSI-C source code library

• Toolchain support includes GCC, Keil uVision, and IAR EWARM


The uMODBUS Toolkit is designed for integration with a wide range of SCADA, industrial and building control systems. It is compatible with standard system level solutions including:

• KEPServerEx – Modbus Suite with RTU, Ethernet and OPC Data Access support

• Building systems HVAC & boiler

• Industrial control & water treatment systems

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