Test Automation for Timing of Modbus Protocol Extension
Morozov, Sergey (2023)
2023
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2023060421118
https://urn.fi/URN:NBN:fi:amk-2023060421118
Tiivistelmä
A communication protocol used for data transmission between devices represents the key element of industrial systems. Modbus is one of the oldest industrial communication protocols that is still widely used in automation and control systems. Several versions of this protocol have been developed, from which the proprietary extension of Modbus RTU is used by Vaisala Oyj.
The aim of this work was to develop the effective approach for test automation of timing issues for the Vaisala extension of the Modbus protocol. Frame timing, timeouts and retries were examined using one of four combinations of tools selected during a pre-study phase: (i) a software Modbus simulator and sniffing software; (ii) a mixed domain oscilloscope; (iii) an FPGA board with a logic analyzer (iv); and a microcontroller with a logic analyzer. The last one was selected as the basis for the development of the test system.
The system was examined from both electrical signal and test automation perspectives. Two test cases were designed and executed on the test system as a proof-of-concept simulating the communication either with a client device or with a server one. The results of this work are proposed to be implemented to the current protocol tester used at Vaisala Oyj, contributing to the protocol quality assurance and the quality control of company products.
The aim of this work was to develop the effective approach for test automation of timing issues for the Vaisala extension of the Modbus protocol. Frame timing, timeouts and retries were examined using one of four combinations of tools selected during a pre-study phase: (i) a software Modbus simulator and sniffing software; (ii) a mixed domain oscilloscope; (iii) an FPGA board with a logic analyzer (iv); and a microcontroller with a logic analyzer. The last one was selected as the basis for the development of the test system.
The system was examined from both electrical signal and test automation perspectives. Two test cases were designed and executed on the test system as a proof-of-concept simulating the communication either with a client device or with a server one. The results of this work are proposed to be implemented to the current protocol tester used at Vaisala Oyj, contributing to the protocol quality assurance and the quality control of company products.