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Modbus/en: различия между версиями
Часть переводимой страницы Протокол Modbus.
FuzzyBot (обсуждение | вклад) (Часть переводимой страницы Протокол Modbus.) |
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=== | === Fundamentals=== | ||
Modbus is a protocol of the applied (seventh) level of the [https://en.wikipedia.org/wiki/OSI_model OSI] model for data exchange, most often between automation devices and is implemented in the form of "request-reply protocol". | Modbus is a protocol of the applied (seventh) level of the [https://en.wikipedia.org/wiki/OSI_model OSI] model for data exchange, most often between automation devices and is implemented in the form of "request-reply protocol". | ||
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There are two protocol specifications: Modbus RTU and Modbus ASCII. An 11-bit character consisting of 1 start bit, 8 data bits (starting with the lower bit), a parity bit (optional), and 2 stop bits if no parity bit is transmitted, or 1 stop bit if | There are two protocol specifications: Modbus RTU and Modbus ASCII. An 11-bit character consisting of 1 start bit, 8 data bits (starting with the lower bit), a parity bit (optional), and 2 stop bits if no parity bit is transmitted, or 1 stop bit if parity bit is transmitted, is transmitted to the Modbus RTU. This character allows you to transfer 1 byte of data. In Wiren Board devices, the parity bit is not transmitted and 2 stop bits are used. In Modbus ASCII, each byte is transmitted in two characters representing the ASCII codes of the lower and upper four-bit byte groups ([http://www.simplymodbus.ca/ASCII.htm пример]). The Modbus RTU allows you to transmit more information at the same serial line speed and it is used in the Wiren Board devices. All further description applies to Modbus RTU. | ||
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Holding Registers and Input Registers are represented by a two-byte word and can store values from 0 to 65535 (0x0000 — 0xFFFFF). | Holding Registers and Input Registers are represented by a two-byte word and can store values from 0 to 65535 (0x0000 — 0xFFFFF). | ||
Input registers are read-only (e.g. current temperature). Storage registers support both read and write (to store settings). Currently, in many devices, particularly Wiren Board devices, these registers are not separated. Commands to read the storage register N and the input register N will access the same value in the address space of the device. | Input registers are read-only (e.g. current temperature). Storage registers support both read and write (to store settings). Currently, in many devices, particularly Wiren Board devices, these registers are not separated. Commands to read the storage register N and the input register N will access the same value in the address space of the device. | ||
===Registers addresses and numbers=== | ===Registers addresses and numbers=== | ||
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[[File:SDM220_Template.png|700px|thumb|center|Template Fragment for SDM220 meter]] | [[File:SDM220_Template.png|700px|thumb|center|Template Fragment for SDM220 meter]] | ||
=== Register reading and writing function codes === | === Register reading and writing function codes === | ||