When is PoE useful?
PoE simplifies cabinet and remote-site installations by carrying power and Ethernet data on one cable. If the central PoE switch is protected by a UPS, network and field-device power can be managed from one point. Check the switch power budget and standards support before installation.
When is DC power suitable?
A reliable existing panel supply can make the 7–28V DC jack a practical choice. Verify voltage tolerance, current capacity, polarity, and protection. Route power wiring appropriately away from noise-producing conductors.
Network connectivity is a separate decision
DC power does not prevent Ethernet use, and PoE does not remove segmentation or security requirements. Select the power method for the physical infrastructure and the network method for reliability and security goals.
Decision summary
Choose PoE when one cable, central UPS protection, and switch-port management matter most. Choose DC when an existing cabinet supply or non-PoE infrastructure is the priority. In either case, include power-restoration behavior and restart time in acceptance testing.