Sequencer Output

Steps through array of output patterns for sequential machine control. This term is essential for understanding ladder logic in industrial automation and PLC programming.

Sequencer Output is part of the visual vocabulary of ladder logic, the relay-derived language that virtually every PLC vendor still supports. Steps through array of output patterns for sequential machine control.

From the PLC's perspective, Sequencer Output executes during the program-execution phase of the scan cycle, where each rung is evaluated left-to-right and the corresponding outputs are updated before the controller writes physical I/O. Understanding when Sequencer Output executes — and how it interacts with the scan cycle — is the difference between code that works in simulation and code that works on real hardware.

For ladder programmers, Sequencer Output is one of the components you reach for instinctively after enough rungs. The visual nature of ladder makes it readable to electricians and operators in a way that text-based languages aren't, which matters in environments where maintenance happens at 2 AM by whoever is on call.