is possible to set the max opening time for a channe in few time?

I don’t quite understand this sentence. Do you mean ‘in fewer time’, like sub-second?

Do you need it to trigger the relay automatically or you can do this manually? If it can be done manually, you can use the Run-Once program and just select a station and set it to be as few seconds as you need. If you need it to be done automatically, or you need sub-second timing, you will need to modify the program.