Phase Block Interface

The standard interface at the Phase Level involves six status signals and five control signals, as listed in the following table.

The following figure shows a general phase block diagram. AVEVA Batch Management with Foxboro DCS components reads the phase block phase status word. Every phase block requires a designated status word.

The phase status word is a dependent or independent block configurable II000n input. The default is II0008. The status word value is either 1, 2, 4, 8, 16, or 32, corresponding to one of the mutually exclusive phase status values.

The phase control word is a dependent/independent block configurable II000n input. The default is II0007. Refer to FB_CONST.inc for assigned values.

A phase block, initially inactive, has a Ready status. When AVEVA Batch Management with Foxboro DCS components issues a Start control signal, the PHASE_EXEC activates the corresponding sequence block and sets the Block Status to Run. If this Run status is not received by AVEVA Batch Management with Foxboro DCS components within a short interval of time (about 15 seconds), AVEVA Batch Management with Foxboro DCS components re-issues the Start control signal.

AVEVA Batch Management with Foxboro DCS components reads the Run status and indicates this status on the appropriate display. When the phase block is done, the HLBL or SFC logic sets the status word to Done. This is done by the TO_INACTIVE SBX function of the corresponding phase. TO_INACTIVE SBX processing is initiated by having an HLBL Abort statement as the last statement in the phase.

If HLBL or SFC logic determines that the phase has not executed successfully, the control word can be set to Hold. The PHASE_EXEC processes this phase control signal by putting the phase in Manual, which activates the TO_MANUAL SBX function in the phase. This puts the phase in a Manual/Active condition and allows a phase to maintain a Held status without the necessity of activating a AVEVA Batch Management with Foxboro DCS components Exception Block. The functionality of a phase block in Held status depends on whether or not Exception Block processing is enabled, and whether or not the particular dependent Sequence Block is using TO_MANUAL SBX processing for a phase Hold condition.

On a RESTART control signal to the phase, the PHASE_EXEC processes this phase control signal by initiating an Auto/Active condition. The TO_MANUAL SBX then continues its processing and sets the phase status to RUN.

On an Abort control signal to the phase, the PHASE_EXEC processes this phase control signal by initiating an (HLBL) Abort for the phase. This activates the TO_INACTIVE SBX processing of the phase which sets the status word to Aborted.

After reading a Done or an Aborted status, AVEVA Batch Management with Foxboro DCS components issues a Reset control signal directly to the corresponding phase block control word. PHASE_EXEC then sets the corresponding block status to Ready.

In the phase block control state diagram, the rectangles show the five control signals that AVEVA Batch Management with Foxboro DCS components sends to phase blocks. The ellipses indicate the six status values that AVEVA Batch Management with Foxboro DCS components expects to see in response to control signals. The lines between the Run and Held states indicate that Foxboro DCS logic can initiate transfers between these two states, independently of AVEVA Batch Management with Foxboro DCS components control actions. However, if Foxboro DCS logic initiates these transitions, it must ensure that correct values for the status words are maintained. If the status word is not maintained correctly, AVEVA Batch Management with Foxboro DCS components shows incorrect phase block states, which could result in batch processing errors.

The PHASE_EXEC acts as an interface between AVEVA Batch Management with Foxboro DCS components and Foxboro DCS equipment logic. The PHASE_EXEC is an independent sequence block positioned after every unit block in every compound. Every compound must have a PHASE_EXEC block to process all sequence block control operations.