Delay between two start buttons.

Hello,
Currently I'm working on a university project based on Star/Delta Starter on PLC.
I wrote program using LD, that switches on the circuit with a motor rotating forward (of course with star/delta starter - here I've used TON timer), then with another start button called "Start back" after pressing "STOP" I can turn the motor on backwards. Everything is working fine. Now I'm trying to figure out how I can set the delay after pressing STOP button (let's say 8 seconds) to block user with pressing START button with another direction.

For example, motor has been started forward, then we press stop and we cannot press "START BACK" until 8 seconds will elapse (to secure the motor).

I was trying to use TOF timer 2 times (one timer for Forward and one for Backwards) but it doesn't solve the problem.
Is there any logic way to solve this problem?

Thanks in advance,


Cheers
 
There is always a logical way to solve a problem,
the harder it appears the greater challenge it becomes.

I must admit the MCC's (motor control centre) I have worked on
the star/delta start is achieved electrically. This is so the starter works
in 'manual' mode without PLC control.

This means you only have one PLC 'run' signal.
For bi-directional motors the PLC has another signal forward/reverse.
Regardless of direction you only need one start inhibit to prevent
repeated starting in either direction.

What are you looking at electrically ?
As I would see one star/delta circuit with a reversing contactor
to swop 2 phases over to achieve reversing.
 
Do you have any inputs to confirm direction of rotation or a zero speed switch? I would inhibit both start buttons until I have confirmed, not assumed, that the motor is not rotating.
 
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