Distributed I/O

More Information about Distributed I/O

Distributed I/O Systems

Distributed I/O systems include small field devices with a wide range of I/O options. This can include counter inputs, digital and analog channels and temperature measurements. These modular devices provide a flexibility lacking in traditional devices, like a PLC, that require a high density channel count and long cable runs. Distributed I/O systems reduce wiring and installation costs as well as allowing for quick machine setup and easy expansion. Distributed I/O can be employed in a physically local arrangement with control and remote I/O in a single enclosure. This setup can provide diagnostics, modularity and short-circuit protection. Other applications may use both rack-mounted and distributed I/O. Rack-mounted I/O supports many points requiring fast response and local devices where wiring is minimal, while distributed I/O connects some remote devices. Systems that extend over a large area may use rack I/O for local control panel indicators, push buttons and related devices while using a distributed system for the remote devices.

FAQs

What are I/O modules used for in control cabinets?

I/O modules are an essential part of control cabinets in industrial automation systems. They are used to interface between the input/output signals from various field devices and the programmable logic controller (PLC) or distributed control system (DCS) that controls the process.

I/O

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. 

Output Signals

Output signals send data out and can be either analog or digital. For example, a digital output could be a run command to a motor. In this case, a signal would be sent that tells a motor to either start or stop. An analog output could be sent to control the speed of that motor, since analog signals have the ability to control a range of values.

Inputs Signals

Inputs signals are received data from either a digital or analog source.  Just like with output signals, inputs can be either digital (which would tell if a motor is running or a door has been opened) or analog (which would be able to tell if the pressure in a pipe is too high or what the level in a water tank is).