The I/O (Input/Output) section of the PLC is the part of the unit that all external devices are connected. The I/O section communicates between the I/O sections and the CPU to carry out programmed functions.
A typical PLC has several I/O sections that allow for a variety of functions to be controlled. We will distinguish between the input and output sections later in this module.
Most PLCs have room for multiple I/O modules on the controller. This allows the PLC to be customized to many different uses, depending on the needs of the user.
Different I/O options can be strung together in order to accomplish a number of tasks.
Several additional types of interfaces should be considered when working with Programmable Logic Controllers.
The following devices may be configured as the interface with the PLC:
– Simple lights
– Proximity switches
– Text messages
Systems that are more complex may include internet-based interfaces that run on supervisory control computers or data acquisition systems.
Human Machine Interfaces (HMI) can also communicate with PLCs as an interface.