Is a connected capacitor discharged when the output is turned off on the PXB series?

Yes. After the output is turned off, the PXB series continues to operate for a period of time to discharge the connected capacitor. The discharge duration depends on the slew rate setting and the output-off impedance setting. The OUTPUT LED also blinks during discharge.

For details, refer to "Impedance Setting When the Output is Off" and "Guide for Required Time for Residual Voltage Discharge" in the User's Manual.