Glossary · System coordination, integration and orchestration
Restart sequence
Also known as: Restart procedure, Recovery sequence
German: Wiederanlaufsequenz
In industrial automation, a restart sequence is the defined series of steps by which a machine or plant resumes operation after a stop, fault, power loss or emergency stop, bringing all parts back to a consistent state before production continues.
- System integration
In one sentence
A restart sequence is the defined series of steps by which a machine or plant resumes operation after a stop, fault or power loss.
Example
After an emergency stop, the restart sequence of a bottling line requires a manual reset, clears half-processed bottles from the filler, homes the star wheels and then restarts the machines from downstream to upstream.
How it applies
- Engineering: Design restart sequences for each kind of stop: normal stop, fault, emergency stop and power loss. After a power loss or emergency stop, machinery safety standards require that restart does not happen automatically; a deliberate reset and start command are needed (see Restart prevention and Manual reset).
- Commissioning: Test restarts from every relevant stop point, including stops in the middle of a transfer or a coordinated motion.
- Operation: A clear, guided restart on the HMI reduces errors and downtime; the restart state of each machine should be visible.
- Documentation: Describe the restart procedure step by step in the operating instructions, including checks before restart (area clear, material removed) and the order in which machines are restarted.
Restart sequence vs. startup sequence
A Startup sequence brings the machine from a shut-down, known state into production. A restart sequence starts from an interrupted, possibly unknown state and must first restore consistency, for example by removing partial products or re-referencing axes.