Which technology links different programmable logic controllers together?

• A. CAN
• B. Modbus
• C. Fieldbus
• D. PLC

Answer: (C)

In an environment where multiple PLCs need to work together, an industrial field network provides the shared communication backbone that links controllers with field devices and with each other. Fieldbus is designed for real-time data exchange and coordinated control across many devices, enabling synchronized operations and centralized monitoring in a distributed control system. This makes it the appropriate technology to connect different programmable logic controllers into a common control network.

Other options don’t fit as the primary interconnect technology in the same way. CAN is a bus used mainly in automotive and some industrial contexts, not as the standard for linking PLCs across a plant. Modbus is a protocol that can run over various physical layers to communicate between devices, but it’s a protocol rather than the overarching network technology that ties multiple PLCs together. A PLC is the device itself, not the linking technology.