Do a PLC traffic light flashing control exercise

Make a traffic light control

1. Controlled by a button, press once to activate, press again to close the cycle.

2.3 lights are on in a cycle,

3. Lights up for 5 seconds, then flashes for 5 seconds.

Push button start and stop control.

Flashing for 5 seconds after control

Control green light

Control yellow light

Red light control.

The next cycle is triggered by the red light signal .

The following is an introduction to the on-delay time S_ODT:

S_ODT (On-delay S5 timer ) starts the specified timer if there is a positive edge at the start (S) input . A signal change is always necessary to enable the timer. As long as the signal state at input S is positive, the timer runs for the time interval specified at input TV. When the timer reaches the specified time without error and the signal state at input S is still "1", the signal state at output Q is "1". If the signal state at input S changes from "1" to "0" while the timer is running, the timer stops. In this case, the signal state at output Q is "0".

If the reset (R) input changes from "0" to "1" while the timer is running, the timer is reset. The current time and the time base are set to zero. The signal state at output Q then changes to "0". The timer is also reset if there is a logic "1" at the R input while the timer is not running and the RLO at input S is "1".

The current time value can be scanned from the outputs BI and BCD. The time value is binary coded at BI and BCD coded at BCD. The current time value is the initial TV value minus the time elapsed since the timer was started.

If the signal state of I0.0 changes from "0" to "1" (rising edge in RLO), timer T5 starts. If the specified two-second time has expired and the signal state of input I0.0 is still "1", output Q4.0 will be "1". If the signal state of I0.0 changes from "1" to "0", the timer is stopped and Q4.0 will be "0" (if the signal state of I0.1 changes from "0" to "1", the time is reset regardless of whether the timer is running or not).