The ornamental design for an I/O module, as shown and described.
FIG. 1 is a front isometric view of an I/O module showing the new design;
FIG. 2 is a rear isometric view of the I/O module showing the new design;
FIG. 3 is a left side view of the I/O module showing the new design;
FIG. 4 is a top view of the I/O module showing the new design;
FIG. 5 is a bottom view of the I/O module showing the new design;
FIG. 6 is a front view of the I/O module showing the new design;
FIG. 7 is a right side view of the I/O module showing the new design; and,
FIG. 8 is a rear view of the I/O module showing the new design.
Broken lines in the drawings are used to depict environment and do not form any part of the claimed design. Where broken lines abut a claimed surface it is understood that those broken lines represent an unclaimed boundary between claimed and unclaimed surfaces. None of the broken lines form any part of the claimed design.