jstolaruk
Lifetime Supporting Member
Unless the process or function you are controlling is as simple as "push and hold button / extend cylinder" it is HIGHLY unlikely that you will be able to encapsulate all the logical requirements for all of the output functions into one rung each.
True, but the goal is to give the technician-electrician, who was not involved in the development, an easy method to track down what the problem is. If a rung is not true because some other condition is not true, then the technician can then follow that condition. Often, an action isn't enabled because the results of another action was not previously achieved.
Again, some of the biggest manufacturers in industry don't allow sequencers or sequencing logic; not because its an invalid method of programming, hardly the case. Its because the maintenance people don't possess the skill set to debug it in a timely fashion. The economical pressures of reduced downtime demands that the programming be made as easy as possible to debug. Hence, the continued use of ladder logic (graphically easy to follow) and the large proportion of programming that is dedicated to diagnostics.