Following are the main Automation & Control suppliers in the world. These are just the PLC, HMI, and other automation equipment providers not the OEM (Original Equipment Manufactures) or Systems Integrators. Those are the companies who implement automation equipment into production lines.
Siemens is a large company involved in three main sectors namely Industry, Healthcare, and Energy. They have over 450,000 employees and over $70 billion yearly revenue. Siemens got involved in Industrial Automation in 1991 by buying the Industrial Systems Division of Texas Instruments.
Right now, Siemens is the largest automation company. This is merely because of their size due to their other sectors. They sell

Allen Bradley is the largest company solely dedicated to automation. Rockwell Automation bought Allen Bradley in 1985 for $1.65 billion. Rockwell’s revenue is over $4 billion and they have over 20,000 employees.
Allen Bradley PLCs and programming languages are known to be the easiest and most convenient one in the industry to use in plants and production line. Allen Bradley has a large selection of products. You can view them all by clicking here.
Fanuc is a business unit of General Electrics. They also make a wide range of automation products that can be found here.
Modicon was one of the first players in the Automation and PLC industry. They have been acquired by Schneider Electric.
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ridhdhesh
January 25, 2010 at 6:58 am
hy i am fresher of electrical engineering , i knowledge of automation ,but i want to increase them ,if u have books on automation please give me by mail,if u have infoamation abt diffrent programming modules ,examples .please mail me,my mail id is ridhdhesh@yahoo.com
Nima Heydarian
January 25, 2010 at 8:07 am
Ridhesh,
I will post a new page on a list of suggested books.
Nima