Siemens SIMATIC PCS 7 Function Manual page 149

The properties specified using the APF Engineering Tool are saved in the
"FB_PARAMATTRIB_XXX" user archive. The structure of this archive determines the input
and output parameters of the corresponding "FB_XXXPA" block.
The parameter set values to be normalized and recalculated and the reference quantity are
defined with the process picture and saved in the "FB_PARAM_XXX" (NORMAMOUNT)" user
archive. If you set the reference quantity to "0", normalization is not executed.
On request, the "FB_XXXPA" block reads the parameter data from the user archives and
triggers normalization/recalculation of the requested data. Data normalization/recalculation is
performed using the "FB_PARAM_CALC_XXX" archive and the relevant functions.
Requesting data
Following a request by a positive edge at the request input "PA.REC_REQ", the data of a data
record written via input REC_ID (parameter set ID) and ARCH_NA /ARCH_NO are read and
written to the output structure "UDT_UA_R_REQ_ST". The read job is activated by setting the
"REC_REQ" bit. Depending on the reference quantity and normalization bit of the individual
parameters, normalization may also be triggered and return the normalized data at the output.
On the OS, the individual parameters are recalculated using the C function
"FB_CalcValueByNormPM.fct". The changed values are supplied to the "FB_UA_RM" block.
Once the read job has been processed, the communication block "FB_UA_RM" writes the
request data (including REQ_ID) and the pointer to the parameter data record to the
"UDT_UA_R_ST" input structure of the block, where it also sets the "NEW_DATA" input bit.
The input data are only assigned to the block's read job if the ID of the block (REQ_ID in the
output structure) matches the "REQ_ID" in the input structure.
Once the input structure data have been assigned to the read job, the data are checked for
validity and plausibility. The system evaluates the following:
● Whether the request data in the input and output structure match
● Whether the data length calculated corresponds to the data length of the outputs at the
block
If the data are plausible and valid, the "NEW_DATA" output is set and the data are written from
the "FB_UA_RM" communication block to the outputs of the block, where they are available
for further processing.
The "NEW_DATA" output is reset by resetting the "PA.REC_REQ" request input.
The "FB_UA_RM" communication block reports any errors it detects during execution of the
read job to the "FB_XXXPA" block. The "FB_XXXPA" block deactivates the read job if an error
occurs ("REC_REQ" = 0). This also happens if the "FB_XXXPA" block itself detects an error.
Normalization/recalculation of the requested data
Following a request by a positive edge at request inputs "L_CAL" or "OP_CAL", the data (e.g.,
QREC_ID (parameter set ID), CALUA_NA / CALUA_NO, parameter output data) are written
to the output structure "UDT_UA_W_REQ_ST". The write job is activated by setting the
"REC_REQ" bit.
The "L_CAL" input can be connected during CFC configuration. The "OP_CAL" input is set
with the "Calculate" button in the faceplate. Whether or not the "L_CAL" parameter is used and
Advanced Process Functions (APF)
Function Manual, 07/2016, A5E38719883-AA
Parameter management
6.1 FB_XXXPA
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