In previous lessons we have discussed the Process Image Input or PII and its purpose. In this lesson we discuss the size of the PII and what will be required of you to know, as the programmer, when it comes to being able to access your I/O when the boundary of the PII is exceeded. Each PLC has a maximum area size of the PII and when exceeded, the addressing for certain I/O must be written differently. This type of addressing or I/O accessing is called Peripheral Input or Peripheral Output and must be utilized in order to access the I/O values. Let’s begin this lesson and find out how to handle Peripheral I/O.