What are PLCs that contain all their different parts and components within a single housing called?

PLCs, or Programmable Logic Controllers, that contain all their components—such as the processor, power supply, input/output (I/O) interfaces, and any other necessary elements—within a single unit are referred to as unitary PLCs. This design provides several advantages, including a compact footprint and ease of installation, making them ideal for smaller applications or where space is limited.

Modular PLCs, in contrast, allow for the addition of various modules to expand functionality but do not house all components within a single unit. Distributed PLCs are designed to spread control across multiple locations or devices, which can add complexity and may not use a single housing approach. Networked PLCs focus on connectivity and integration with other systems in a networked environment, but they too do not encapsulate all components in one housing. Understanding these distinctions helps clarify why unitary PLCs fit the description provided in the question.