The implementation of this Industrial Internet of Things (IIoT) access gateway for the ModBusE protocol aims to improve the data flow at the level of slots and acquisition cycle, using multiprocessor architectures. In this article, the gateway implementation approach was done using a BeagleBone Black board. BeagleBone Black uses the Sitara AM335x processor from Texas Instruments. The AM335x Sitara consists of a 32-bit ARM Cortex A8 RISC processor that operates at a frequency of up to 1 GHz and two 32-bit real-time PRU (Programmable Real-Time Units) processors that operate at a frequency of 200 MHz. The acquisition cycle of the ModBus Extension protocol based on a master slave architecture will be implemented on one of those two real-time PRU processors. The high-power ARM Cortex A8 processor can be used to implement OPC UA server and client. The aim is also to develop a specific AM335x Sitara driver that allows fast transfer between the two processors ( PRU – ModbusE master / slave and ARM Cortex A8 RISC - OPC UA server and client ). From previous work related to ModBus Extension it has been shown that the performance obtained with Cortex Mx architectures were approximately 58% useful data from the acquisition cycle with STM32F407 at 10.5 Mb / s, 51% useful data from the acquisition cycle with STM32F746 at 27Mb / s, and 70% useful data from the acquisition cycle with LPC4300 which, however, has 2 Cortex M0 and M4. M0 only deals with protocol. However, Cortex M4 and M7 does not have sufficient resources to implement high - performance OPC UA server and client. The solution presented in this article allows the implementation of the ModBus Extension Master/Slave protocol with better communication channel usage performance than those previously presented (higher than 70%), using real time PRU (Programmable Real-Time Units) processors.  At the Industrial Internet of Things (IIoT) connection, the 1MHz ARM Cortex A8 processor offers superior performance to the M4, M7 cortex for implementing OPC UA server and client specifications (specifications supported by Industry 4.0), or other IIoT middleware such as MQTT, AMQP, REST, DDS, CoAP (6LowPAN), etc.

Acknowledgments: This work is supported by the project “ANTREPRENORDOC”, in the framework of Human Resources Development Operational Programme 2014-2020, financed from the European Social Fund under the contract number 36355/23.05.2019 HRD OP /380/6/13 – SMIS Code: 123847.