Chapter 5 PLC basics

What are the two broad categories of memory space in a PLC processor?

Program files and Data files.

What does the program files section of a PLC's memory store?

Ladder logic programming.

What function does the Data file portion of the memory serve?

Stores input/output status, processor status, various bit statuses, and numerical data.

What is the function of the Examine If Closed (XIC) instruction?

It allows rung continuity if the associated memory bit is set to 1, mimicking a normally open relay contact.

What does a value of 1 or 0 in memory indicate in the context of XIC instructions?

1 indicates true/on condition, while 0 indicates false/off condition.

How are input image tables used in PLC programming?

They store the on/off status of connected discrete inputs.

What is the purpose of the Output Energize (OTE) instruction?

It signals the PLC to energize or de-energize the output based on the status of the associated memory bit.

What occurs during each program scan cycle of a PLC?

The processor reads inputs and updates outputs based on the user program.

What is the impact of scan time on a PLC's performance?

A longer scan time may prevent the PLC from detecting fast input changes.

What are branch instructions used for in PLC programming?

To create parallel paths of input condition instructions, allowing for more complex logic evaluation.