Most readers do not support 24 VDC so there is risk of damaging the reader
Mercury MR50 single reader board powered with 24 VDC and a card reader
Continuum hardware (ACXs and AC1s) typically have a jumper to configure 5 or 12 VDC for reader power.
Mercury board MR52 can select 12 VDC for reader power with jumper J2 when it's powered with 24 VDC.
The MR50 CANNOT be cpmfigured for 12 VDC reader power. If the MR50 is powered by 24VDC, it will automatically pass 24 VDC to the reader terminal board. CONNECTING A NON 24VDC READER IN THIS CONIFIGURATION WILL DAMAGE THE READER.
Readers that require different voltage or have high current requirements should be powered separately.
Note: multiclass readers are often being deployed and these cannot be powered solely from the reader terminal, so separate reader power is used.