I have an mp select IIIP. Using the front panel, the bed temp maxes out at 60. I let it preheat, start printing and it sometimes let’s me go up to 80 while it’s printing. I want to set it at 80 and forget about it.

If you set the bed temperature to 80 degrees in your slicer the printer will automatically heat up to 80 degrees when you choose a file to print from the SD card or over USB.

Send M140 S80 as gcode, either as a short print snippet or via a host program like Pronterface