Understand Phase Block Operations

Here is a logical progression that the phase block logic should follow. The phase block uses the phase control bits to proceed through the code as long as the particular phase status bits are satisfied. You must also write code to provide the phase block with interlock and alarm conditions.

The sequence of events for a typical phase block is as follows:

1. When a phase block is inactive, the phase status is Ready. The only way that this cannot be true is when the phase block is interlocked.

2. When the block is required to operate, the batch control system sends any required formula parameters followed by a Start command.

3. When the Start command is received, the phase block enters the Run state and processes the block logic.

4. During the remainder of the operation, the block can be put into the Held state through the Batch Control System phase control Hold command, or if a critical alarm condition occurs.

5. From the Held state, the phase block can either be restarted or aborted.

   The restart command resumes the phase block operation.

   The abort puts the phase block in the aborted state and ends the block operation. The batch control system monitors this Aborted status, and sends a phase Reset command to return the block to the Ready state.

6. If the phase block continues to completion, the status becomes Done.

7. The batch control system monitors the Done status, and similar to the Aborted status, sends a phase Reset command to return the block to the Ready state.

This sequence of events is followed each time that the phase block is included in the current Batch Control System recipe configuration.