Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

126 Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems
Table of Index-Size Codes for Non-Ranged Mode
I-size
Code
Size in
bits
Meaning in Request or Response
containing Data Objects
0 no index No indexing. Objects are packed
directly.
1 8
2 16
3 32
Objects are prefixed with an index of
this length.
The application of the non-ranged mode differs depending on whether the I-size code is
zero or non-zero.
For I-size = 0, the specified number of objects are called for, or provided. This method
is useful for requesting or responding with a limited amount of data at one time, perhaps
if the outstation could provide more information than could be handled at once by the
master station.
For I-size = 1, 2 or 3 a list of specific data objects is provided. This is used when particular
data objects, or points, are required rather than a whole range of data objects.
REQUEST MESSAGE OBJECT GROUP
RANGE DATA
GROUP VARIATION QUALIFIER
N
INDICE 1 INDICE 2 ... INDICE N
G
V
1 8 LSB MSB 14
37
107
1 1 1 2 1 1 1
I-size = 1 => 8-bit index size
Q-code = 8 => 16-bit range value = object count N
RESPONSE MESSAGE OBJECT GROUP
RANGE DATA
GROUP VARIATION QUALIFIER
N
INDICE 1 DO 1 INDICE 2 DO 2 . . . INDICE N DO N
G
V
1 8 LSB MSB 14
37
107
1 1 1 2 1 x 1 x 1 x
Note: Size of data objects x = determined by object group / variation definition
Q
Code
Range Value
Size (Bits)
7 8
8 16
9 32
Referencing
Mode
Non-Ranged
Mode
Interpretation of Qualifier Code
Notes
Specifies a list of unrelated points. The Range
field contains the number of points referenced.
I-size = 0: No indexes, points only
I-size = 1: Indexes are 8 Bit
I-size = 2: Indexes are 16 Bit
I-size = 3: Indexes are 32 Bit
REQUEST MESSAGE OBJECT GROUP
RANGE
GROUP VARIATION QUALIFIER N
G
V
0 7
1 1 1 1
I-size = 0
Q-code = 7 => 8-bit range value = object count N
RESPONSE MESSAGE OBJECT GROUP
RANGE DATA OBJECTS
GROUP VARIATION QUALIFIER N DO DO
G
V
0 7
0 1
1 1 1 1 x x x
Note: Size of data objects x = determined by object group / variation definition
DO
2
...