I have a weekly timer that the user can set via front panel eg 15:00 to 22:00 daily.

But I need another output that goes high 2 hours after time starts and low one hour before timer ends..

Can one use a block to correctly set the output 2 hours after start and 1 hour before end ?

Could use two timers but will require the user to correctly set the start and end times based on the times entered for the first timer, so prone to error and not ideal.

Actually, sorry, I meant 2nd timer 2 hours on before weekly timer on (to allow gas to level out) and off 1 hour before weekly timer off.

If it helps timer will only be used during normal working hours(ish) so no calculations around midnight and crossing days will be required.

Also accuracy of 2nd timer is not too important 15 minutes (or 30 minutes !) is fine as long as 2nd timer start time is at least two hours and off time is at maximum 1 hour.

Only that we are talking about the same thing:

Example:
First weekly timer
On: 5:00 clock
Off: 22:00 clock

Second weekly timer (automatic calculation)
On: 3:00 clock (2 hours before turn on first weekly timer)
From: 21:00 clock (1 hour before turn off second first weekly timer)

Is that correct?

Edit: second relaced by first

Yes.

Thank you.

Stay the switching times within a day or are they across the day?
Example:

On: 5:00 clock
Off: 22:00 clock

or

On: 23:00 clock
Off 15:00 clock

How do I access the timer setting in an FBD ?

I was thinking about starting an hour counter at midnight and when it got to within two hours of timer start time, enable the 2nd output.

And do similar for off time, counter gets within 1hour of timer off time disable the 2nd output.

Accurate to an hour, but fine for this application.