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IEC 104 south plugin (client/master)

IEC 104 redundancy server modes

The MZ Automation lib60870 server provides 3 different modes regarding the support of redundant connections and events queue handling:

• The default mode (CS104_MODE_SINGLE_REDUNDANCY_GROUP) allows only a single active client connection.
• The second mode (CS104_MODE_CONNECTION_IS_REDUNDANCY_GROUP) allows multiple active client connections.
• The third mode (CS104_MODE_MULTIPLE_REDUNDANCY_GROUPS) allows multiple active client connections while preserving events when no client is connected.

In the case of this design, the south plugin will be implemented with CS104_MODE_MULTIPLE_REDUNDANCY_GROUPS server mode.

This mode allows multiple active client connections while preserving events when no client is connected. In this mode clients can be assigned to specific redundancy groups. The assignment is based on the IP address of the client. A redundancy group can have multiple simultaneous connections but only one of these connections can be active. The number of activated connections is restricted by the number of redundancy groups. Each redundancy group has a dedicated event queue.

It can be set with the CS104_Slave_setServerMode function:

CS104_Slave_setServerMode(slave, CS104_MODE_MULTIPLE_REDUNDANCY_GROUPS);

multiple redundancy groups example

draw.io Diagram
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IEC 104 Protocol stack configuration

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