Delay in turning on two different start buttons in Star/Delta starter on PLC

Question

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

Marko Buršič · Answer

ErrBim is an error if there is no signal from motor protection switch (Bimetal NC), when set it has to be cleared by an acknowledge signal (Proc.ErrClearPulse)
StartBtn is a start button NO, that is evaluated with positive change, when it switches from 0->1
StopBtn is a stop button NC
ESTOP is the emergency stop signal NC, if not present it stops all
S_ON is a intermediate flag
K_ON is the output for the main contactor
InterlockT is a timer that prevents a quick re-start, Off Delay
StarT is a timer for star/delta changeover, On Delay
K_Star is an output for star contactor
K_Delta is an output fro delta contactor

EDIT:
It could be also in one single network, depends on your engineering software. If you need fwd/bkw is almost the same, except you do split into two sections, then you OR the InterlockT with fwd OR bkw contactor output.

Delay in turning on two different start buttons in Star/Delta starter on PLC

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