The SIGLENT SPD series of power supplies have only positive voltage and current setpoint values. That is, you can select voltages or currents that are from 0 to the max value (0-32 V, for voltage.. as an example for the SDP3000X/X-E).
Here are the suggested wiring configurations to achieve both positive and negative potentials at the device-under-test (DUT):
NOTE: It is critical to select wire that can handle the full current and voltage of the supply. You can find numerous wire gauge recommendations, but here is one from Engineering Toolbox: https://www.engineeringtoolbox.com/wire-gauges-d_419.html
Floating Wiring Configuration:
Grounded Wiring Configuration: