Automation or industrial automation or numerical control is the use of control systems such as computers to control industrial machinery and processes, reducing [[wysiwyg_imageupload::]]the need for human intervention. In the scope of industrialization, automation is a step beyond mechanization. Whereas mechanization provided human operators with machinery to assist them with the physical requirements of work, automation greatly reduces the need for human sensory and mental requirements as well. Processes and systems can also be automated. Automation plays an increasingly important role in the global economy and in daily experience. Engineers strive to combine automated devices with mathematical and organizational tools to create complex systems for a rapidly expanding range of applications and human activities. In some industries proper maintenance of the controlling system or industrial devices is crucial to deliver an uninterrupted output. So to reduce the maintenance costs and to optimize critical monitoring system GSM Based Industrial Automation Technology is used.