Glossary · System coordination, integration and orchestration
Blocked state
Also known as: blocked condition, output blocked
German: Blockierzustand
In production line coordination, a blocked state is the condition of a machine or station that cannot release its output because the downstream machine or buffer is not ready to accept it. The machine itself is ready to work but must wait.
- System integration
In one sentence
A machine is in a blocked state when it could work but cannot release its output because the downstream station or buffer is full or not ready.
Example
The labeler stops feeding bottles because the case packer downstream is jammed; the labeler HMI shows “blocked by downstream.”
How it applies
- Engineering: Distinguish blocked, starved and faulted in the machine state model so line control and performance analysis can tell whether a machine lost time through its own fault or through its neighbors. In PackML-based machines such external conditions are commonly handled in the Suspended state.
- Operation: Line OEE analysis uses blocked times to find the real bottleneck (see Bottleneck coordination): a blocked machine is usually downstream-limited, not the problem itself.
- Documentation: HMI texts and manuals should name the cause (blocked by downstream) and tell the operator where to look instead of showing a generic stop message.
Blocked vs. starved
A blocked machine cannot get rid of its output. A starved machine has no input because the upstream machine or buffer is empty. Both are waiting states, not faults, and they point in opposite directions along the line.