[allenp]

Hello guys,
we've got Stama Robodrill MC14 with Fanuc16i and intermittent errors 1018 (TCZ switch is welding) and 1016 (MCC is deffective).

When I'm looking at alarm 1018 in ladder I see it misses one condition to activate which is R0301.2 to become active.
When I look at this R0301.2 coil I see following line (rung) which puzzles me... How can contact R0301.2 activate itself after timer value expires?
https://ibb.co/9qPMYVt

What really causes R0301.2 coil to activate to 1, actually what causes timer to start counting?
What is the difference between R0301.2 contact (condition to start timing) and R0301.2 coil?
Isn't R0301.2 just bit number 2 of memory address R0301?

Thanks in advance for anything useful in understanding this logic.

[Shoprag]

Contact R300.4 activates the timer. R301.2 is used to latch the output on (R301.2) until estop goes low.

[allenp]

Thank you so very much!

[Algirdas]

until estop goes low.

physical input: X0008.4

the difference between R0301.2 contact (condition to start timing) and R0301.2 coil?

If trying to touch it, it is actually the same bit in the execution memory. However, there is a difference. It is read as input at the start of PLC cycle. The status updated as an output ( not physical ) of function at the end of PLC cycle. Since it is just a regular bit.
There are more conceptions about PLC cycle arrangement, this is just a basic one.

Isn't R0301.2 just bit number 2 of memory address R0301?

exactly.