The ornamental design for a multiplexslideplatedevice, as shown and described.
FIG. 1 is a perspective view of a multiplex slide plate device showing my new design;
FIG. 2 is another perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a right side view thereof;
FIG. 7 is a top view thereof; and,
FIG. 8 is a bottom view thereof.
The broken lines immediately adjacent to the shaded areas that define unshaded regions depict the bounds of the claimed design and form no part thereof. The broken lines that are shown within the broken line boundaries depict portions of the multiplex slide plate device that form no part of the claimed design.