Indicator lamps in a control system are commonly driven by how many manual discrete logic outputs?

Indicator lamps in a control system are commonly driven by how many manual discrete logic outputs?

• A. Four manual discrete logic output
• B. Two manual discrete logic outputs
• C. One manual discrete logic output
• D. Eight manual discrete logic outputs

Answer: (A)

Indicator lamps are used to show several key statuses at a glance, and each lamp needs its own control signal from the control logic. With discrete outputs, you wire one output to each lamp so you can light or extinguish each lamp independently. Four lamps is a standard in many panels because it provides enough information to distinguish common operating states—like power/ready, manual versus auto, running versus stopped, and fault—without needing extra wiring or complex multiplexing. If you used only one or two outputs, you couldn't portray all important states; using more than four adds cost and clutter unless there are additional status conditions to display. Therefore, four manual discrete outputs to drive indicator lamps is the typical arrangement.

Indicator lamps are used to show several key statuses at a glance, and each lamp needs its own control signal from the control logic. With discrete outputs, you wire one output to each lamp so you can light or extinguish each lamp independently. Four lamps is a standard in many panels because it provides enough information to distinguish common operating states—like power/ready, manual versus auto, running versus stopped, and fault—without needing extra wiring or complex multiplexing. If you used only one or two outputs, you couldn't portray all important states; using more than four adds cost and clutter unless there are additional status conditions to display. Therefore, four manual discrete outputs to drive indicator lamps is the typical arrangement.