Overview OCPP Central System



This function block turns the controller into a central system for charging stations according to OCPP 1.6J. The charging stations connect to the controller themselves; the controller never dials out to a charging station. This matches the roles defined by the standard: the central system issues all commands, the charging station reports its state.

The block is created once per project. It opens the network port and manages the connections of all charging stations. A second block has no function and reports an error. An individual charging station is operated with the Wallbox OCPP block.

In the charging station, enter ws://<IP of the controller>:8887/<identity> as the address of the central system. The identity can be chosen freely (the ChargeBoxId in OCPP) and must be entered identically in the Wallbox OCPP block. If a charging station connects with an identity that is not yet known, it is accepted and written to the log - this is how the identity used by the charging station can be determined.

Important: The connection is unencrypted (ws://). The block is intended for operation inside your own network. The port must not be reachable from the internet.



Inputs

FG
 Enable
 Reserved for a later extension. The server runs independently of this input.

Outputs
SB
 Server ready
 Output is 1 when the network port is open and charging stations can connect.
AL Number of charge points Number of charging stations currently connected.
AV Number of charging sessions Number of charging sessions currently running across all charging stations.
ER Communication error Output is 1 when the port could not be opened. Most common causes: the port is occupied by another program, or there is a second OCPP Central System block in the project. The block retries every 10 seconds.

Parameters
Port
 Network port on which the charging stations are expected. Default 8887. OCPP does not prescribe a port, but 8887 is widely used.
Path prefix If the field is empty, any path is accepted and the last path segment is used as the identity of the charging station. If a prefix is entered, only connections whose path starts with it are accepted. Useful when the port has to be reachable from outside.
Authentication Authentication of the charging station when connecting:
  • None: every charging station is accepted.
  • User and password: all charging stations use the same user and the same password from the following parameters.
  • Password per charge point: the user name is the identity of the charging station, the password is entered in the Wallbox OCPP block.
Not every charging station supports authentication.
User User name for authentication.
Password Password for authentication.
Heartbeat interval Time in seconds given to the charging station as the interval between two heartbeats. Default 300 seconds, minimum 60 seconds.
Ping interval Time in seconds in which the central system checks the connection on its own. This is necessary because some charging stations do not send heartbeats while a charging session is running, so a broken connection would otherwise go unnoticed. Set to 0 to switch the check off.
Connection timeout Time in seconds without any reception after which the connection is dropped. The charging station then reconnects on its own.
Command timeout Time in seconds within which the charging station has to answer a command. After that the command is considered lost. It is not repeated: the charging control writes a current value in the next cycle anyway.
Max. charge points Maximum number of charging stations connected at the same time. Further connections are refused and written to the log.
Meter value interval Time in seconds in which the charging station should send its measured values. The factory setting of the devices is usually too slow for this - the Fronius Wattpilot sends only every 60 seconds by default, so the surplus control would get a new power value only once a minute. The central system changes the value when connecting, and only if it differs from the setting of the charging station. With 0 the setting of the charging station is left unchanged.
Accept unknown charge points With Yes, charging stations without a matching Wallbox OCPP block are accepted as well. This is needed during commissioning to find out the identity of the charging station. With No an unknown charging station is rejected but stays visible in the log.
Debug With On all sent and received messages are written to the log.


See also general parameters of all function blocks.