Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

298 Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems
ASDU types may be provided. This makes sense as the device need only have the
capabilities required to support its own functions. Other parameters such as communications
speeds may be configurable items, that may be set to one of a number of possible
values as required by the user.
To be able to check that a particular device is compatible with the specification chosen
for a full system, a means of describing all of these parameters, and optional selections is
required. IEC 60870-5-101 provides for this by including an interoperability section
within the standard. This is section 8 of IEC 60870-5-101 Amendment 2. This is intended
to be used by manufacturers to describe the specific functionality of their systems.
9.2.2 Interoperability document
The reader will benefit from examining either a blank interoperability statement by referring
to the standard, or a completed one available for IEC 60870-5 compliant equipment.
Due to copyright restriction this has not been included within this text.
The interoperability section has the following sections. These each have check boxes
or list items that allow specification of the details for a particular device or system.
System or device selection:
• System definition
• Controlling station definition (master)
• Controlled station definition (slave)
Network configuration:
• Point-to-point
• Multiple point-to-point
• Multi-point-partyline
• Multi-point-star
Physical layer:
Link layer:
• Transmission speed (control direction)
• Transmission speed (monitor direction)
• Balanced or unbalanced
• Address field of link; octets, structure
• Maximum frame length
• Standard assignment of ASDUs to class 2 (types 9, 11, 13, 21)
• Special assignment of ASDUs to class 2 (list)
Application layer:
• Common address of ASDU; 1 or 2 octets
• Information object address; octets, structure
• Cause of transmission; 1 octet, or 2 with originator address
• Selection of ASDUs; full list, mark with X, R or B for using in standard,
reverse or both directions
• Cause of transmission codes for each type (table with boxes)