The E-X50 supports connection of a half-damper pedal, but does not support half-pedaling technique. When using the Roland DP-10 (sold separately), set the function switch to the "Switch" side before turning on the power. See also: Does it support half-pedaling? and The pedal switch is working in reverse.
See also the related Q&A "Does it support half-pedaling?" and "The pedal switch is working in reverse."