Transfer of integrated totals (counter interrogation)
Here you can unpack the complete PLC sources: TcPlcLibIEC870_5_101Slave_TutorialSample.zip
General count transfer model:
The actual values are added by counters. Via a re-store command that is either received by the central station or generated locally (in the substation), the actual values can be re-stored (copied) periodically into re-stored values. After freezing, the recorded value is either reset to zero (logging of incremental values), or the counter continues adding up (logging of counter readings).
Application objects with counts are assigned to groups. The groups are frozen individually, reset, or transferred. The central station sends count query commands to the substation. The task to be carried out (FRZ) and the group (RQT) are specified in an ID field of the command (QCC).
The allocation of the application objects to the individual groups (1 to 4 or general) is specified via the group flag parameter during configuration. There are four operating modes for recording counter readings and incremental values. Each mode includes notes about the configuration of the system parameters or the application objects.
Mode A: local freeze with spontaneous transfer
The substation internally initiates freeze or freeze with reset. The frozen counts are transferred spontaneously, once the freeze or freeze with reset function was executed. In this mode the central station does not issue any count query commands.
Configuration of the system parameters:
bPerFRZ := TRUE
tPerFRZCycle := T#60s
The first parameter activates local freeze or freeze with reset. The second parameter specifies the cycle time with which freeze or freeze with reset is carried out (e.g. every 60 seconds).
Configuration of the application objects:
- The IEC870_GRP_SPONTOFF group parameter must not be set, since it would prevent spontaneous data transfer of the counts.
- The count is frozen if the IEC870_GRP_LOCFREEZE group parameter was set.
- The count is reset if the IEC870_GRP_LOCRESET group parameter was set.
- Local freeze or freeze with reset is carried out simultaneously for all groups (1 to 4 or general).
Operating mode B: Local freeze with counter interrogation
The substation internally initiates freeze or freeze with reset. The central station queries the frozen counts via count query commands. In this case the central station must not use freeze or freeze with reset in the command ID field (FRZ=0). The counts are queried generally or in groups 1 to 4.
Configuration of the system parameters:
bPerFRZ := TRUE
tPerFRZCycle := T#60s
The first parameter activates local freeze or (and) reset. The second parameter specifies the cycle time with which freeze or freeze with reset is carried out (e.g. every 60 seconds).
Configuration of the application objects:
- The IEC870_GRP_SPONTOFF group parameter must be set. The counts are not to be transferred spontaneously to the central station.
- The count is frozen if the IEC870_GRP_LOCFREEZE group parameter was set.
- The count is reset if the IEC870_GRP_LOCRESET group parameter was set.
- Local freeze or freeze with reset is carried out simultaneously for all groups (1 to 4 or general).
Operating mode C: The central station initiates freeze, freeze with reset, or reset
The central station periodically issues a count query command to the substation for controlling the freeze or (and) reset process. This command does not result in a count transfer. The central station sends a subsequent count query command for collecting the frozen counts. This is similar to operating mode B.
Configuration of the system parameters:
bPerFRZ := FALSE
tPerFRZCycle := T#60s
Local freeze or (and) reset must be deactivated. The second parameter is ignored.
Configuration of the application objects:
- IEC870_GRP_SPONTOFF must be set. The counts are not to be transferred spontaneously to the central station.
- The IEC870_GRP_LOCFREEZE and IEC870_GRP_LOCRESET group parameters must not be set. The central station initiates freeze or (and) reset.
- The counts can be assigned to individual groups (1 to 4 or general) and queried (IEC870_GRP_REQCOGEN, IEC870_GRP_REQCO1, IEC870_GRP_REQCO2, IEC870_GRP_REQCO3, IEC870_GRP_REQCO4).
Operating mode D: The central station initiates freeze and (or) reset, and the frozen values are transferred spontaneously
This mode is a combination of the count command from the central station as in mode C and spontaneous transfer of the counts as in mode A.
Configuration of the system parameters:
bPerFRZ := FALSE
tPerFRZCycle := T#60s
Local freeze or (and) reset must be deactivated. The second parameter is ignored.
Configuration of the application objects:
- The IEC870_GRP_SPONTOFF group parameter must not be set, since it would prevent spontaneous data transfer of the counts.
- The IEC870_GRP_LOCFREEZE and IEC870_GRP_LOCRESET group parameters must not be set. The central station initiates freeze or (and) reset.
- The counts can be assigned to individual groups (1 to 4 or general) and queried (IEC870_GRP_REQCOGEN, IEC870_GRP_REQCO1, IEC870_GRP_REQCO2, IEC870_GRP_REQCO3, IEC870_GRP_REQCO4).