Industrial Communication Systems

36-1

36.1 Introduction

e Modbus protocol was created in 1979 by Modicon* as a means of sharing data between their PLCs

(programmable logic controllers). Modicon took the approach of openly publishing its specication and

allowing its use by anyone without asking for royalties. ese factors, along with the simplicity of the pro-

tocol itself, allowed it to become the rst widely accepted de facto standard for industrial communication.

Although

initially

a

proprietary

protocol

controlled

only

by

Modicon,

it

is

since

2004

controlled

by

a

community

of

users

and

suppliers

of

automation

equipment,

known

as

Modbus-IDA.

is

nonprot

organization

oversee ...