Verilog modelling of Modbus TCP at 100 mbps

Abstract

With the continuous development of industry automation, industrial control systems and programmable logic devices are being widely used in the manufacturing production. Machines are required to work either in connection to each other or remotely controlled at a centralized control room using Internet of Things (IoT), Supervisory Control and Data Acquisition Systems (SCADA) or other communication means. Among the many industrial networking protocols, Modbus TCP is widely adopted. Software implementation of Modbus TCP network is common in the industry. Although software does the job, it is a burden to the processor. There are also Modbus TCP hardware modules selling in the market. But dedicated hardware incurs high cost and not scalable for any feature change. Hence, this project aims to analyse and design a hardware Modbus TCP client and server communication node with the help of RTL-ASMChart and Petri Net. It will be implemented at 100Mbps Ethernet speed within the appropriate power, performance, and area. This design is coded in SystemVerilog and validation is done in Quartus ModelSim simulation. Running testbench in ModelSim and Wireshark show the design is function as expected, after it can be compiled and fit into the target Cyclone V FPGA. Timing closure and throughput expectation of 100Mbps is met in Quartus, with power consumption of around 350mW. Round trip test results showed that RTL designed TCP module has speed improvement over the software TCP method of Windows operating system.