What failures can affect an Equipment Sequence?
There are two kinds of failures:
Equipment Sequence
failures and Equipment Phase
failures.An Equipment Sequence failure is when the Equipment Sequence detects a condition resulting from either an equipment phase generating a phase failure (as part of executing the phase’s control routine) or an unexpected condition that interferes with the sequencing program’s ability to coordinate the sequence.
An
Equipment Phase
failure is when the Equipment Phase
of an active step within an Equipment Sequence
executes a Phase Failure (PFL) instruction. The instruction includes a parameter set by the user to identify the failure.Failures should be cleared before restarting the
Equipment Sequence
, otherwise the sequence will immediately become failed again. When a failure is present, a red flag appears in the upper left hand corner of the diagram frame, and the Failures
field shows the failure. The following table shows the sequence failures.Failure | Failure Type | Description |
The Equipment Phase associated with a sequence step is not in IDLE state. | Equipment Sequence | The next step (or steps) that must be made active because the Equipment Sequence is advancing. That is, a transition expression became TRUE and is associated with a phase that is not IDLE. By definition, a phase must be IDLE for an Equipment Sequence to use it. |
The Equipment Phase associated with a sequence step is either Inhibited or Not Scheduled. | Equipment Sequence | The next step (or steps) that must be made active because the Equipment Sequence is advancing (for example, a transition expression became TRUE) is associated to a phase that is INHIBITED or NOT SCHEDULED. By definition, a phase must be IDLE for a sequence to use it. |
The Equipment Phase associated with a sequence step could not be commanded as it was overridden. | Equipment Sequence | An Equipment Phase owned by the Equipment Sequence has its attachment overridden by a Logix Designer user. |
The Equipment Phase associated with a sequence step executes a PFL instruction. | Equipment Phase | In the Equipment Phase routine being executed, the user has coded a PFL instruction to flag a failure condition. A parameter of the PFL instruction identifies the failure. |
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