Can not monitor online S7-1200 (all networks go grey)

Dear all,

Today, I encountered a issue when monitoring S7-1200 program.

At first, I could monitor as normal. After that, I change some settings (system and clock memory).

Then I added new networks and downloaded software to PLC.

Then I monitored again but the issue happened: All networks went grey, I could not monitor anymore.

Besides, when I changed sensor signals, input leds changed but output leds did not.

I attached photo of my laptop screen in this post.

Please give me a way to fix this. 

Thanks a million!

Hello,

It's difficult to say.

Can you monitor OB1?

Perhaps FC4 is not active?

Best regards,

Wizard

That was my problem; I didn't call the function into the main. 

Thank you for the tip.