Drop down list box in op77b

Hi,

I have 20 numbers of motors.I want to start the motor from the op77b by selecting the name of the motor in OP and press start push button in my panel.what i thought was i will create a drop down list box in op.when i select name of the motor and press the push button the motor should start.
But i cannot able to do above in the op77b.

is there any way i can create drop down list box??