Practical_modern_SCADA_protocols_-_dnp3,_60870-5_and_Related_Systems

230 Practical Modern SCADA Protocols: DNP3, 60870.5 and Related Systems
Note that the action specified by FRZ is applied to the group selected by the RQT code.
The four values of freeze code FRZ each specify a different operation immediately following
the counter read. These are:
Continue to count from value. The read is just a snapshot
Stop counting and hold value as read
Clear the count to zero and stop counting
Clear the count and continue counting from zero
QPM
Qualifier of parameter of measured values
This information element is used in setting local parameters of measured values. The KPA
code defines the type of parameter, and the other bits determine whether local changes are
permitted, and whether the parameter is to be activated.
7 6 5 4 3 2 1 0
POP LPC KPA
Key
KPA Kind of Parameter UI6[0..5]
= Not used
= Threshold value
= Smoothing factor (filter time constant)
= Low limit for transmission of measured values
= High limit for transmission of measured values
= Reserved for future standard definitions
= Reserved for special use (private range)
LPC Local parameter change BS1 [6]
= No change
= Change
POP Parameter in operation BS1[7]
= Operation
= Not in operation
QPA
Qualifier of parameter activation
7 6 5 4 3 2 1 0
QPA
Key
QPA UI8[0..7]
= Not used
= Activation of cyclic transmission of object
= Reserved for future standard definitions
= Reserved for special use (private range)
QOC
Qualifier of command
7 6 5 4 3 2
S/E
QU