Modbus Server stack and Modbus Client stack

Modbus is one of the most widely used industrial protocol stacks. As an open-standard, this protocol has been used for major industrial process automation over many decades. Modbus can work in Server and Client mode (Modbus Slave & Modbus Master) and is used in products such as PLCs, Variable Speed Drives, HMIs, Data Acquisition systems etc.

Embien offers Modbus protocol stack for both use in server and client configurations in accordance to the Modbus Application Protocol Specification V1.1. Our Modbus Server stack and Modbus Client stack implementation supports all the function codes defined by the protocol and supports extension via APIs too. Physical layers supported include RTU, ASCII and TCP/IP.


Features of RAPIDSEA Modbus protocol stack

Embien has been in the forefront of technological evolution for more than the past 13+ years helping customers realize their vision. Embien has developed a unique skill set that helps us work across domains, even benefiting customers with cross-industry knowledge and experience. Backed by an enthusiastic team and led by industry veterans, our offerings are unparalleled in quality and speed of execution in the field of turnkey embedded product design. The lwip modbus stack port is as effective as running the stack on .NET/Linux platforms.Renesas, NXP, TI, Microchip MCUs etc..

Cross Platform

Cross Platform

Available for both Baremetal and RTOS on all major embedded architectures including ARM, x86, SH, PowerPC, AVR, PIC

Ease of Use

Ease of Use

Written in MISRA compliant 'C' in a thread safe way, our server and client can be accessed via clearly defined APIs.

Domain Expertise

Small footprint

Occupies less than 2KB of ROM and about 60 bytes of RAM giving valuable space for your applications and business logic.

Simple Licensing

Simple Licensing

Our Royalty Free Licensing Model, tied to each MCU part provides you great flexibility in deploying it across any number of products

Supported Function Codes

Our Modbus stack supports the following function codes

Function Code Name
01h Read Coils
02h Read Discrete Inputs
03h Read Holding Registers
04h Read Input Registers
05h Write Single Coil
06h Write Single Register
0Fh Write Multiple Coils
10h Write Multiple registers
2Eh Write Data By Identifier

Apart of these standard function codes, it is possible to add new and extend the features based on the application requirements.

No code Modbus RS232, Modbus RS485 and Modbus TCP Configuration

In addition to the stack, Embien also offers no code development using Flint where the Modbus register address to be supported/accessed can be defined using Flint Editor and downloading the code on to the target will start working as the server/client. Extensive configurations such as Baud rates, Data Formats, IP address, etc. are supported. Modbus RTU gateway, Modbus RTU to Ethernet/IP, Ethernet/IP to Modbus TCP Protocol converters can be quickly developed using this approach. For more details, refer to Flint System Configurator page.

Flint Modbus Configurator

Unparalleled Cross-Platform support

Our Modbus stack is supported across a wide range of platforms and compilers

Renesas MCUS and MPUs

RAPDISEA Modbus stacks are supported for the following Renesas MCUs and MPUs

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    RA8/RA6/RA4 and RA2

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    RL78 Series

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    RX72 and RX6Xx

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    RZ MPUs


All the leading MCU and MPU families from the NXP and erstwhile Freesscale

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    LPC Series

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    i.MX RT

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    iMx6/8 Series

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    QorIQ Series

Infineon MCUS and MPUs

Industrial and General purpose processing families from Infineon including

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    XMC 4000

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    XMC 7000

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    XMC 1000

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    FM4 Series

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    AURIX Tricore

ST Micro MCUS and MPUs

MCUs and MPUs from all spectrum of computing offered by ST Micro

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    STM32F Series

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    STM32L Series

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    STM32G Series

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    STM8 Series

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    STM32 MP


Texas Instrument ARM based MCUs and higher end SITARA/OMAP processing platforms

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    AM24x Series

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    MSP430 Series

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    C2000 Series

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    AM64x/AM65x MPUs

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ARM, PIC and Atmega family of MCUS and MPUS offered by Microchip are supported

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    AVR Family

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    PIC24/PIC32 Series

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    PIC32 MCUs

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    SAM A5/A7 MPUs

Other MCUS and MPUs

MCUs from other leading vendors such as

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    Espressif ESPxx

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    Nuvoton MCUs

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    Silicon Labs EFM32

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    AD MCUs

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Compilers and toolchains

Our stacks can be readily compiled for different toolchains including

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    GHS Multi

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    IAR Embedded Workbench

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    Microsoft Visual C++

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    Keil MDK

Why RAPDISEA Modbus Stacks?

Up in 30 minutes

Up in 30 minutes!

Our Modbus protocol stacks are used by various clients and we have deployed them over many time. With this experience, we have created an optimal flow, where the customers can quickly incorporate and validate in their design in a matter of just half an hour. Guided by our expert team and extensive documentation, make your device speak the language of Modbus.

Reliable and Proven

Reliable and Proven!

Designed and developed by architects in the industrial automation domain software development, our stacks are written in compliance with the standard. Optimized for both speed and size, the Modbus Server and Client stack has been validated both by certification software and practically in the field with hundreds of devices, PLCs, SCADA systems, HMIs etc.

Low Code Development

Low Code Development!

Leverage the power of low-code development without writing a single line of code to enable the Modbus functionality. With our Flint tool, developers can drag and drop the stack module, configure the registers and associated data with the convenience of the mouse. Only the data from business logic has to be updated via only 2 API's.

Modbus related offerings

Digital Transformation

Embien has been helping companies transition to the industry 4.0 era and achieve exceptional returns. Aided by advancement in AI, ML and data analytics, our digital transformation services help businesses improve operational efficiency by optimizing supply chain, forecasting and managing right amount of inventory, predicting downtime and planing preventive maintenance, collecting right data and effectively using them to further improving the process and attain sustainable environment.

Protocol Converters

Our team has developed numerous protocol converters supporting products from generations and OEMs speak seamlessly to each other. Our designs have covered Field buses like Modbus, Profibus, HART etc, industrial networks like Ethernet/IP, BACnet, Profinet, EtherCAT etc, wireless connectivity technologies like WiFi, LoRA, Bluetooth, Wireless HART, ZigBee etc. In conformance to protocol specific certification and general CE, UL, IPC ratings, these converted deliver value across every functional aspect of the industry.

Product Engineering

Digital twins are essentially a digital representation of physical object or process that are available for visualization and review at any instant of time. With data continuously captured via Internet of Things (IoT) technologies from each part of the system, the cloud based technologies are used to recreate a dynamic models of the system. With wide range of applications, Digital Twins are being widely deployed with Embien helping realizing them for customers in automotive and manufacturing industries.

Protocol Stacks

With advent of smart factories, many components of the industrial manufacturing process has to be online thereby increasing the attack surface. With potential down times impacting productivity, revenue and reputation, it calls for experts to help reduce vulnerabilities and protect the businesses. Embien is in the forefront of the embedded cyber-security with special focus on smart industry 4.0. With our security-first approach our team has conducted cyber-security audit, identified open points and closed them for many customers.


If you are coder, we have a detailed list of APIs with example implementations, that can be readily integrated in your application. If you are not, it is even easier. Leverage our Flint System Configurator to configure and utilize the same.

RAPIDSEA Modbus Stack runs on top of the Serial port for RTU/ASCII and TCP/IP for Modbus/TCP. The clearly defined liwer level API's to interact with these interfaces are to be provided. That will do!

Sure. The stack is available in source code format and can be cross compiled to platform of your choice. Then implementing the underlying Serial/TCP functions, the system is Modbus-ready!

The Modbus stack can be purchased in any combination of functionality - Server/Client and transport - RTU/ASCII/TCP. Combo options are avaiable at attractive price points.

We offer it in a royalty-free model with no hidden charges whatsoever. Pay us once and you can use it for any number of products with the licensed MCU part number. If you look for alternate licenses, feel free to reach out to us.

Embien can do the porting for you and help run the Modbus stack on the new target MCU.

Yes, do not hesitate to contact us for an evaluation version of our library. While it provides all the functional features, it is a time limited version.

Yes, definitely! We already have working ports up and running

Our stack occupies about 30KB of ROM for full features and less than 50 bytes of RAM excluding the stack area.

Our stack finds wide applications in various devices such as PLCs, HMIs', Protocol Converters, SCADA systems, Variable Frequency Drives, Soft starters, String Monitoring Units, Sensors and Transmitters, etc.


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Want a no-code Modbus Server stack and Modbus Client stack?
Try our RAPIDSEA Modbus protocol stack now!

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