Can I reduce the level of the voltage resolution for PCR-MA series to less than 0.1 V?

No, you cannot. PCR-MA series doesn’t have the function to reduce the level of the voltage resolution to less than 0.1 V. However, if you install the optional analog interface board (EX08-PCR-MA), you can finely change the output voltage by the external analog signals. For the details, read “Control Using External Analog Signals (Option)” for the user’s manual of PCR-MA series.