setup for ssr 220v large heat bed

Hi I have a RAMPS 1.4 Mega 2560 my printer bed is 900mm x 400mm I have the choice of two 400mm x 400mm silicone heaters 220v 200w each or a 800mm x 400mm silicone heater 220v 500w at the moment I am using a ssr 3 to 30v dc to 220v ac with a pdi to control it temp I would like to just use the ssr on my ramps board but cannot get it two switch it on or off with marlin configuration file
Any help would be appreciated thanks


the attach image is a diagram that i use to setup my ssr pdi

Look at this video.

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Prusa i3 Rework - Ramps 1.4 - E3d Lite6 - Full Graphic LCD Controller

thanks that is just what i was looking for just need to set up marlin.ino