IEC 104 operation mode

The IEC 104 driver can be operated as client and server at the same time. The server modus is enabled via config entry tcpServerPort or tlsServerPort (for secure connections, see IEC 104 TLS).

According to IEC 104 protocol level the driver has the default role of the controlling station on a connection established as a client and controlled station on a connection accepted as server.

IEC 60870 application telegrams (e.g. messages or commands) are always triggered by the application. For example End Of Initialization telegram is not sent automatically.

When the IEC driver is accepting a connection it is searching for a matching configured hostname. If it does not find a matching entry, the connection will be closed. In order to support clients with dynamic IP addresses which are always changing, there is the following possibility:

Configure a hostname with prefix "_ANY_" (e.g. _ANY_host0) for a connection data point _IecConnection. This connection can be assigned to any client, as long as its free, i.e. no other client occupies the connection. Thus, it is possible to create a pool of connections for unknown clients. The remaining part of the hostname can be defined at will, however it must be unique (e.g. _ANY_host0, _ANY_host1).

For example: Five clients with unknown IP addresses shall connect to the driver, you have to create five connection data points and define an unique hostname with _ANY_ prefix for each of them.

For handling configurations where controlled stations are actively establishing TCP connections, the configuration option "Change Role" must be selected on the configured connection.