Method for allocating addresses from node device in Modbus communication network

Abstract

The invention discloses a method which allocates addresses for the slave node devices in the Modbus communication network; the method includes the steps that the master node device and the slave node devices are initialized; the address of a slave node device is set and the number of the slave node devices is set; the master node device sends the address polling message to each slave node device periodically; when a slave node device receives the address polling message with the data which is the same as the address of the slave node device, the slave node device returns a message which carries the address of the slave node device to the master node device; when the master node device judges that the address of the slave node device is different from the stored address of the master node device, the master node device stores the address of the slave node device; when the number of the addresses of the slave node devices stored in the master node device is equal to the number of the slave node devices, the flow ends. The method which allocates addresses for the slave node devices in the Modbus communication network can conveniently examine that if the address allocation of the slave node devices is completed correctly.

Description

technical field [0001] The invention relates to a method for allocating addresses, in particular to a method for allocating addresses for slave node devices in a Modbus communication network. Background technique [0002] Fieldbus technology has been increasingly used in industrial sites. The Modbus bus is more and more widely used because of its advantages such as simple protocol, easy implementation, high cost performance and high reliability. [0003] The Modbus communication network based on the serial link is a master-slave network, and only one master node and a maximum of 247 slave nodes are allowed in the serial network. In the Modbus communication network, the command / response communication method is adopted. The master station sends out a request, and the slave station responds to the request and sends back data or status information. The slave station cannot actively send information. The various information frame formats defined by the MODBUS protocol describe ...

AI Technical Summary

Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide a method for assigning addresses to slave node devices in a Modbus communication network, which overcomes the shortcoming that it is impossible to check whether the address assignment of slave node devices is completed correctly in the prior art

Images