Test Equipment
Dwyer Instruments is a company that primarily focuses on pressure, flow, temperature, and air quality. They manufacture test equipment that is designed around those measurement principles. So, when I think about tools that are absolutely essential for ensuring accurate and reliable measurements and performance of systems in HVAC, environmental, and process industries, I think about Dwyer.
A global leader in electronic test tools, Fluke is well known for its wide array of testing devices. These include digital multimeters, oscilloscopes, and thermal imagers—just a few of the essential test instruments that Fluke provides for professional use across the electrical, industrial, and automotive fields.
Test equipment for energy management and industrial automation is provided by Lovato Electric. Their product line includes power analyzers, multimeters, and other monitoring devices that help industries measure and manage electrical parameters.
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).