D-2 T35 Transformer Protection System GE Multilin
D.1 IEC 60870-5-104 PROTOCOL APPENDIX D 
D
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
Cause of Transmission:
 One Octet
 Two Octets (with originator address). Originator address is set to zero if not used.
Maximum Length of APDU: 253 (the maximum length may be reduced by the system.
Selection of standard ASDUs:
For the following lists, the boxes indicate the following:  – used in standard direction;  – not used;  – cannot be
selected in IEC 60870-5-104 standard.
Process information in monitor direction
 <1> := Single-point information M_SP_NA_1
 <2> := Single-point information with time tag
M_SP_TA_1
 <3> := Double-point information M_DP_NA_1
 <4> := Double-point information with time tag
M_DP_TA_1
 <5> := Step position information M_ST_NA_1
 <6> := Step position information with time tag
M_ST_TA_1
 <7> := Bitstring of 32 bits M_BO_NA_1
 <8> := Bitstring of 32 bits with time tag
M_BO_TA_1
 <9> := Measured value, normalized value M_ME_NA_1
 <10> := Measured value, normalized value with time tag
M_NE_TA_1
 <11> := Measured value, scaled value M_ME_NB_1
 <12> := Measured value, scaled value with time tag
M_NE_TB_1
 <13> := Measured value, short floating point value M_ME_NC_1
 <14> := Measured value, short floating point value with time tag
M_NE_TC_1
 <15> := Integrated totals M_IT_NA_1
 <16> := Integrated totals with time tag
M_IT_TA_1
 <17> := Event of protection equipment with time tag M_EP_TA_1
 <18> := Packed start events of protection equipment with time tag M_EP_TB_1
 <19> := Packed output circuit information of protection equipment with time tag M_EP_TC_1
 <20> := Packed single-point information with status change detection M_SP_NA_1