The connection status of each channel of the module is put in a double-word descriptor that is mapped to the CPU memory of your PLC program facility.
You assign a valid CPU memory address to which the connection status descriptor is to be mapped.
NOTE: For IEC 60870-5-104 and DNP3 server witch configured to connect with more than one client, each client has an independent connection status, and they store in sequence in CPU memory.
The descriptor occupies 2 consecutive CPU memory words. The following tables show the information that the connection status descriptor contains.
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Bit 31
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Bit 30...Bit 1
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Bit 0
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Session #31
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session #30...session #1
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session #0
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For the IEC 60870-5-101in balanced mode and the DNP protocol, the connection status descriptors are set to 1 to indicate that all slaves are connected. Then the corresponding bit is reset to 0 after the command is sent without the reception of a valid response.
NOTE: If connection status really matters, configure parameter "Test Frame Period" with a none zero value for IEC 60870-5-101 protocol, "Link Status Period" for DNP3 protocol
