I am trying to use a Basic PLC with Click Software from AutomationDirect to control a screw type powder feeder based on weight. The scales are RS-232 output and the PLC has RS-232 inputs so I think I am fine there. I need something to control the DC motor controlling the screw in an on/off format. Also need a keypad to control what weight the motor will turn off at.

Summary : PLC used to control screw powder feeder with a DC motor. Keypad to change weights, something to turn motor on off when "Start" button is pressed and turn motor off when scale output reads the typed in number.

 

Just wanted to clarify, an AC motor can be used as well, this is ground up design, so whatever is easier.

 

Are you trying to operate to a continuous feed rate? For example, X pounds per hour or are you trying to deliver a batch of X pounds? An SCR can be used to control the speed of the screw motor and you can use an output from the plc to control the on/off function of the SCR, which is controlling the speed of the screw feeder. This would suffice for a gain-in -weight batch system design but if you need a weight loss continuous system then that is a whole different algorithm, which is very complex to implement.

 

I need something to control the DC motor controlling the screw in an on/off format. Also need a keypad to control what weight the motor will turn off at.

If you just want on/off format for the screw then you just need a suitably sized contactor. C-more HMIs seem to be made to go with the Click PLCs so that would allow you to enter the weight