Siemens SICHARGE D Operating Instructions Manual page 11

Power limit fallback
In case of loss of communication detected by the charger and the ELMS, the charger switches to
the power limit fallback setpoint. This signal is sent by the ELMS to the charger via the software
interface. The following diagram depicts the flow of signals related to the power limit fallback
and handshake.
Heartbeat monitoring (optional)
The communication interface relies on TCP protocol which attempts automatic re-connection
and is slow to report communication loss. Heartbeat monitoring is an optional sub-feature and
its main purpose is to have fast and reliable communication loss monitoring.
It needs to be enabled by ELMS via Boolean flag in control word. Once activated, charger
shall send a pulse train of fixed on and off duration (e.g., 1 sec. each) as flag in status word.
ELMS needs to send this signal back to Charger via another flag in control word.
In case the heartbeat from ELMS control word stops toggling for a certain duration of time,
charger sets the Heartbeat Error flag in status word and a changover to power limit fallback
occurs.
External Load Management System
Operating Manual, 07/2022, A5E52045935-AA
Description
2.2 Sub-Features
9