Ideally, their input should be recorded in a manner that is easy for them to
use and understand. Frequently, the process engineers work with the control
systems design group to establish the entire control system—both the analog
and the on-off control—using the P&IDs and one or more of the forms of
logic documentation. Later, the programmers work with the control systems
design group to implement the logic, sometimes long after the process engineers
have defined the intended operation. When the electrical group handles
on-off control, the Logic Diagram can be the interface enabling the electrical
group and the control systems group to complete the design of the
interlock system cooperatively.