Glossary · Electrical engineering and control panels
I/O system
Also known as: Remote I/O system, Modular I/O, Distributed I/O
German: I/O-Module
In industrial control, an I/O system is the modular arrangement of I/O modules, bus coupler or head station, backplane and power distribution that connects a group of field signals to a controller, either locally in the rack or remotely over a fieldbus or industrial Ethernet.
- Control panels
In one sentence
An I/O system is the modular set of I/O modules, head station and backplane connecting field signals to a controller, locally or remotely.
Example
Each machine module has its own remote I/O system with a PROFINET head station, so it can be tested separately and connected to the main controller on site.
How it applies
- Engineering: Remote I/O reduces wiring by placing modules close to the field devices. Consider update times and Latency over the network, power supply segments for inputs and outputs, and diagnostics reported to the controller.
- Commissioning: Addressing or device names must match the controller configuration. Mixed module types within one station have to follow the manufacturer's order and power rules.
- Documentation: Document each station with its modules, order, addresses, network name and power segments. The list entry "I/O modules" is a plural variant of I/O module; this entry covers the modules as a system.
I/O system vs. controller
The I/O system only acquires and outputs signals. The controller executes the program. Some remote I/O head stations also run local logic, which should be documented as such.