I need to control a conveyor (driven by Micromaster 440) from a PC program using SFC14/15. The scheme will be: Supervisors PC ->(ethernet)-> S7-1200 ->(profibus)-> Micromaster 440. At the moment, Micromaster's output frequency is controlled via a potentiometer (analog inputs) by the "field" operator. The problem is that sometimes the operator increases the conveyor speed in order to do his job faster and this affects the production negatively. The "supervisor" wants to be able to limit output frequency using the PC program.
Of course I've seen the list of MM440 parameters and I know about P1082, but I've discovered that, unfortunately, MM440 should be stopped before the new value of P1082 takes effect. In my case it's preferable to be able to change the value on the run. Fortunately, it seems that P0757 - P0760 - (input scaling) can be changed on the run, but this parameter has sign "first confirm", which means that
the “P” button on the operator panel (BOP or AOP) must be pressed before the changes take effect.
But the MM440 has only one slot for the Profibus/BOP/AOP panel and I'll be using Profibus. So, in this case, what will be the behavior of mm440 like? I want to believe that, perhaps, this condition is not obligatory when using profibus panel...
I would opt for a solution where the operator no longer operates the belt speed directly but tells the S7-1200 PLC a what speed he would like the belt to run (either by using 2 +/- buttons or a pot-meter). The PLC can then control the speed of the belt (either by analog output or 2 digital (+/-) outputs).
As an added bonus you can stop the belt when it is accidentally left on and things like that...