Anyone has an idea for this Logic

Thread Starter


Joined Feb 26, 2014
Im using logic gates to do the logic then do the PLC

Let’s say I have 3 motors, Motor A, Motor B and Motor C “All could be online, offline”
If I turn-on Motor B first, it is going to be Primary motor.
And If I turn on Motor C next, it is going to be Secondary
And if I turn on Motor A, it should be Tertiary..
If Motor C turned off then Motor A should become Secondary and Motor C will be tertiary even if it is in OFF mode and so on …. I will have six scenarios

Motor A Motor B Motor C
Primary Secondary Tertiary
Primary Tertiary Secondary
Secondary Primary Tertiary
Secondary Tertiary Primary
Tertiary Primary Secondary
Tertiary Secondary Primary


Joined Nov 23, 2012
Could you put some context around this? Like, why do you need this? Is the primary, secondary, tertiary lable for software or do you bed a complete solution in discrete logic chips for some reason.

A better explanation will get you an answer vs ignored.


Joined Jul 18, 2013
what is the reason for (discrete?) logic gates, why not go directly to PLC?
Is this PLC as in Industrial definition or a μp?