When troubleshooting a PLC system, what would typically indicate that a switch is malfunctioning?

A malfunctioning switch in a PLC (Programmable Logic Controller) system is often indicated by the input status not changing as expected. In a properly functioning setup, the state of the switch—whether it is open or closed—should directly reflect on the PLC's input status. If the switch is functioning correctly, toggling it should result in a corresponding change in the input status that the PLC reads.

When the input status remains constant despite actions taken on the switch, it suggests that the PLC is not receiving the expected signals. This could occur due to various reasons such as an electrical fault within the switch itself, broken connections, or issues in wiring. Monitoring the input status is a fundamental step in troubleshooting, as it provides clear evidence of the switch's operational state.

Other indicators, while they may suggest issues within the system, do not directly point to a malfunctioning switch. For example, a continuously running motor might be caused by various factors unrelated to the switch itself. Similarly, an indicator light being on can be related to other circuit components, and a program executing without errors does not imply all hardware, including switches, is functioning correctly. Therefore, observing the input status is the most effective means to diagnose potential malfunction of a switch in this context.