A Diagnostics Plate is being assembled as part of the linac commissioning plan for the Oak Ridge National Laboratory Spallation Neutron Source (SNS). The D-Plate will be positioned directly after the first Drift Tube Linac (DTL) tank, where the H beam energy will be 7.5 MeV. A full suite of beam diagnostic instrumentation is planned, including profile, current, phase, energy, and emittance measurements. The D-Plate is designed to operate up to the full duty factor of the linac, or up to 16-kW beam power. Until the spallation neutron target is completed several years later, this will be the last time the facility can be operated at full current and duty cycle.