Frame length
Two octets
Maximum length L
(number of octets)
Structured
Unstructured
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
9, 11, 13, 21
<1>
A special assignment of ASDUs to class 2 messages is used as follows:
Type identification
Cause of transmission
(In response to a class 2 poll, a controlled station may respond with class 1 data
when there is no class 2 data available).
10.1.5
Application layer
Transmission mode for application data
Mode 1 (Least significant octet first), as defined in 4.10 of IEC 60870-5-4, is used
exclusively in this companion standard.
Common address of ASDU
(System-specific parameter, all configurations that are used are to be marked with
“X“.)
One octet
Two octets
Section 10
1MRS757105 B
Appendix 2 IEC 60870-5-104 interoperability
80
RER601/603
Technical Manual
