Safety Sensors
Industrial and commercial applications use safety sensors as essential parts to ensure safety. They are designed to protect people and equipment in hazardous areas by detecting risks and initiating appropriate responses when something or someone may be in danger. Safety sensors work with other safety devices, like safety switches and safety light curtains, to make up the comprehensive safety systems that one hopes will keep them safe in hazardous areas. For example, in machinery, safety sensors might be used to detect if something or someone is in a danger zone and shut down operations to avoid an accident.
In particular applications, such as garage door openers, safety sensors use infrared or other technologies to detect obstructions in the path of the door. When the door is in motion and an obstruction is detected, the door's movement will automatically reverse and the path of the door is unobstructed before the door is permitted to re-enter its downward travel. Safety edge sensors perform a similar function but are installed on the door itself or along the edge of a gate. Safety sensors are designed to be installed easily and connected directly to the door-control apparatus. They are also wired in such a way that reliability and compatibility with other safety solutions are enhanced.
More Information about Safety Sensors
The safety sensors available today cover an array of environments and applications—from industrial equipment to automatic doors. They appear in many forms from many manufacturers, each offering tailored solutions to their particular safety problem. Underneath all those appearances, though, the modern safety sensor has a few key enhanced capabilities. First, it's able to detect things like human presence with greater reliability and under a wider set of conditions. Second, it's much tougher and more capable of functioning in environments that are anything but safe for the object doing the detecting.
Analog and Digital Control Signals: The Basics
Digital Signals
Digital signals are represented in either a true or false. There is no gray area with digital signals. An example of this might be a light switch. A light switch is either on or off. Another example of this might be a motor that is running or not running. Digital signals can be generated with both AC and DC circuits with varying voltages, currents and resistance. Some practical examples of using digital signals in an industrial environment might be if a pump is running or not running or a whether a valve is open or closed.
Analog Signals
Analog signals convey information in the form of a range. A light switch might be on or off as a digital signal, but a dimmer switch would be an analog signal. It can be on or off, but it can also be somewhere in between. A practical example of using analog signals in an industrial environment would be if there is a need to measure the level of a tank; whether it's full, empty or somewhere in between. Analog signals can take many different forms with some of the more common being a 4 to 20 milliamp signal or a 0 to 5 or 0 to 10 volt signal.
Communication
Communication in a device can either be sent or received. Whether that data is sent or received depends on the type of information. Is there a need to monitor the status of something? If so, an input needs to be received about that information. Is there a need to control something? If so, an output needs to be sent about what needs to occur. Receiving inputs and setting outputs are both things that can be accomplished by using both digital and analog signal types. Therefore, the signals are referred to as analog outputs (AO), analog inputs (AI), digital inputs (DI) or digital outputs (DO).