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6-2 UR FAMILY – COMMUNICATIONS GUIDE
INTEROPERABILITY DOCUMENT CHAPTER 6: IEC 60870-5-104 COMMUNICATION
6
3. PHYSICAL LAYER
Transmission speed (control direction)
Transmission speed (monitor direction)
4. LINK LAYER
When using an unbalanced link layer, the following Application Service Data Unit (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:
 A special assignment of ASDUs to class 2 messages is used as follows:
5. APPLICATION LAYER
Transmission mode for application data
Mode 1 (least significant octet first), as defined in Clause 4.10 of IEC 60870-5-4, is used exclusively in this companion
standard.
Common address of ASDU
 One Octet
 Two Octets
Information object address
 One Octet  Structured
 Two Octets  Unstructured
 Three Octets
Unbalanced interchange
circuit V.24/V.28 standard
Unbalanced interchange
circuit V.24/V.28 recommended
if >1200 bits/s
Balanced interchange circuit
X.24/X.27
 100 bits/sec.
 200 bits/sec.
 300 bits/sec.
 600 bits/sec.
 1200 bits/sec.
 2400 bits/sec.
 4800 bits/sec.
 9600 bits/sec.
 2400 bits/sec.
 4800 bits/sec.
 9600 bits/sec.
 19200 bits/sec.
 38400 bits/sec.
 56000 bits/sec.
 64000 bits/sec.
Unbalanced interchange
circuit V.24/V.28 standard
Unbalanced interchange
circuit V.24/V.28 recommended
if >1200 bits/s
Balanced interchange circuit
X.24/X.27
 100 bits/sec.
 200 bits/sec.
 300 bits/sec.
 600 bits/sec.
 1200 bits/sec.
 2400 bits/sec.
 4800 bits/sec.
 9600 bits/sec.
 2400 bits/sec.
 4800 bits/sec.
 9600 bits/sec.
 19200 bits/sec.
 38400 bits/sec.
 56000 bits/sec.
 64000 bits/sec.
Link transmission procedure Address field of the link
 Balanced Transmission
 Unbalanced Transmission
 Not Present (Balanced Transmission Only)
 One Octet
 Two Octets
 Structured
 Unstructured
Frame Length (maximum length, number of octets): Not selectable in companion IEC 60870-5-104 standard