ProSoft Technology 5201-MNET-101S - Manual (Page 131)

IEC-101 Slave ♦ ProLinx Communication Gateway IEC 60870-5-101 Slave Interoperability Statement
IEC 60870-5-101 v3 Slave (Firmware version 3.xx) Protocol Manual
ProSoft Technology, Inc. Page 131 of 159
August 6, 2010
6.4 Link Layer
(Network-specific parameter)
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 link
 Balanced transmission  Not present (balanced transmission only)
 Unbalanced transmission  One octet
 Two octets
 Structured
Frame length

Unstructured
25 to 252 Maximum length L (number of octets)
6.5 Application Layer
6.5.1 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.
6.5.2 Common Address of ASDU - 101S
(System-specific parameter)

One octet  Two octets
6.5.3 Information Object Address
(System-specific parameter)

One octet  Structured
 Two octets  Unstructured
 Three octets
6.5.4 Cause of Transmission
(System-specific parameter)

One octet  Two octets (with originator address)
6.5.5 Length of APDU - 101S
(System-specific parameter, specify the maximum length of the APDU per
system)
The maximum length of the APDU in this protocol implementation is 252
(default). The maximum length may be reduced by the system.
The maximum length of APDU per system is 255.