The CEI IEC 62056-21 Standard: Powering Local Meter Data Exchange
: It specifies the use of an optical interface (using infrared light) or electrical interfaces like RS-232 or RS-485. The optical port is particularly iconic—the small circular "eye" found on the front of most digital meters. Operational Modes : CEI IEC 62056-21
While newer wireless technologies like NB-IoT and LoRaWAN are popular for remote reading, IEC 62056-21 remains indispensable for three reasons: The CEI IEC 62056-21 Standard: Powering Local Meter