The RP-IO module has a built-in power supply designed to accommodate a nominal operating voltage of 24 VAC at 50/60 Hz or 24 to 30 VDC input power.
The built-in power supply is based on a full-wave rectified, isolated design, which is complemented with electronic protection components for transient protection, overload protection, and EMC compliance.
To power the I/O module, you can use a transformer or a DC power supply:
Class 2 (EN 60742) transformer supplying a nominal 24 VAC at 50/60 Hz
DC power supply supplying a nominal 24 to 30 VDC with the required output power
The 24 VAC/VDC power input is galvanically isolated from the electronics. This minimizes the risk of damage due to earth currents and permits the input power to be wired without concern for polarity matching.