Dear MGP,

thank you for reply and the circuit you send me.
I 've studied the circuit a lot to fully understand how it works but i didn't manage to understand how to do the loop after restart.

I'm sure it's something quite easy but at this time i'm unable to find it.

I send you my tweak to this circuit asking you if possible to fill it with the appropriate missing function.

Thanking in advance
John

Dear MGP,
thank you for your concern.
My apologize for google translation about "school" project.
In fact i've finished school many years before!
I 'm trying to do a project for a friend as cheaper as possible.
Arduino mega is the cpu i 'm thinking about to do the job together with an RTC shield and also a 8 relay board. If possible I would like to show (optional), the current time to an oled spi display.
The system is a solar panel moving (not tracking) system.
It is little more complicated than mentioned before though.
The construction is already made and consist of an inverter omron MX2 and the mechanical construction too.
I was thinking use a modbus RTU commands to control the inverter but i didn't find a good way to engage modbus commands via arduino.
Anyway here is the working task:

When the RTC reached 6 pm, starts the motor by sending Forward command to inverter via a dry relay contact to direction WEST. When WEST limit switch reached, it send a RUN Reverse command through dry relay contact to inverter and the motor runs CCW until the EAST switch reached and then goes to sleep mode until 6 pm and does the loop again.
Of course there are safety switches like NC contacts from thermal or emergency which enables STOP command to the inverter and LED indicators.
I preferred to ask help for solving the start-stay problem but since the project is going i must find solution as sooner as possible.
Also i 've made a simple design in 3D to help clarify the all system.

Thanking in advance
John

Dear GMP,
thank you once more fro your concern and i appreciate it.
I 've tested your version and it works like a charm!

I have many questions though about my tweaked circuit.

1) I add a MANUAL MODE function just to override the orbit and regain position in case of thermal event. I' ve done the simulation and it was correct.

2) I did assign pins for arduino mega to test the circuit but even the .ino sketch compiled well, the timing process didn't work at all. It is working only the Manual overriding mode though.

3) Is it possible to un-assign all pins and do this job from beginning?

Thanking in advance

PS I send you my tweaked version and the arduino compiled files as well.

I can't help you with Arduino, I never use it because I'm a PIC user.

Un-assign all pins... simply select "no microcntroller" at the bottom of the menu.

BTW. I hate contacts in the middle of a rung, professional programmers use an inputcontact with an internal relay with the same name.
If something went wrong then you can see immediately which contacts are pressed or free.

Yes you are right. I was used to program like relays and i forgot that i'm doing PLC programming.
Now i' ve fixed it and it works quite well.
About modbus your mention before, it's a very delicate opportunity to control the inverter remotely.
If i was able to push a switch and send a coil command like "RUN_FW" via RS485 protocol, i would be very pleased.
But since i didn't make it to work, i will keep on the main task.

PS I send the so far circuit for reference.

In rung 12 the start button x_manual latch with R_manual contact. When i re-position the panel into the desired orbit, i drop thermal and it does stop the latch. Then reset the thermal again to continue the orbit.

I 've managed to implement an DS1307 RTC clock code into .ino sketch and i will try to fetch the tm.hour function for the 6pm check.

The time is displayed to an 4 pins OLED and so far it works.