(Network-specific parameter, mark all used options with an “X“. Specify the maximum frame length. If a non-standard assignment of class 2 messages is implemented for unbalanced transmission, indicate the Type ID and COT of all messages assigned to class 2.)
Frame format FT 1.2, single character 1 and the fixed time-out interval are used exclusively in this companion standard.
Link transmission procedure |
Address field of the link |
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Balanced transmission |
Not present (balanced transmission only) |
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Unbalanced transmission |
One octet |
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Two octets |
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Structured |
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Unstructured |
Frame length |
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Maximum length L (control direction) |
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Maximum length L (monitor direction) |
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Time during which repetitions are permitted (Trp) or number of repetitions |
When using an unbalanced link layer, the following ASDU types are returned in class 2 messages (low priority) with the indicated causes of transmission:
The standard assignment of ASDUs to class 2 messages is used as follows: |
Type identification |
Cause of transmission |
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A special assignment of ASDUs to class 2 messages is used as follows: |
Type identification |
Cause of transmission |
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