Hearbeat signal to PLC without MultiTask

Hi all.

I am trying to setup a communication signal with my PLC to four robots with a heartbeat but I do not have multitasking to create a background task that always runs. 

Is there a way to mirror an input to an output? That way I could have a heartbeat from my PLC to my robot, and have an output from my robot to the PLC that is equal to the input value.

Does anyone have any tips for checking whether I still have communication with my controller from the PLC? 

Thank you.