Phase Block Memory Guidelines

Use the following memory guidelines to make phase blocks consistent and portable:

• Determine the number of phase blocks needed for the entire system and increase this number by 20% to allow for expansion.

• Determine the number of global interlocks needed for the entire system and increase this number by 20% to allow for expansion. This is the number of discrete data points to allocate for global interlocks.

• Determine the number of global alarms needed for the entire system and increase this number by 20% to allow for expansion. This is the number of discrete data points to allocate for global alarms.

• Determine the number of outputs needed for the entire system and increase this number by 20% to allow for expansion. This is the number of discrete data points to allocate for manual operation of global outputs.

• Should future expansion beyond the 20% cushion become necessary, follow the memory guidelines within each expansion section and add them to the end of the previous section.

• If you can configure the control system memory, determine all phase block logic requirements (such as timers and counters), and allocate memory accordingly while also allowing for expansion.

• Whenever possible, pack phase control and status bits within words to make more efficient use of control system memory.