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3.3.3 Initialization of the FB_PARAM function block
The module should be initialized before the first instruction is processed. For this
purpose only an FB invocation without instruction must occur, i.e. the FB inputs
Read, Write, Save and Factory_default must have the value FALSE. This
initialization step should be carried out after each instruction has been processed.
Internal static variables are initialized as a result and the module is set to a defined
status.
3.3.4 Instruction processing
When processing a parameter instruction, it must be ensured that only one instruction
is present at the FB input, as parallel processing is not possible. This input must have
the value TRUE until the instruction processing is complete. This is indicated at the FB
output Done with the value TRUE. In order to process the next instruction, no
instruction should occur at the FB input for one invocation. The FB output Doneis then
reset as confirmation and the new instruction can follow immediately.
No active communication takes place with the drive between two instructions.
3.3.5 Renaming modules
The modules can be renamed if necessary. For this purpose the instance data blocks
DB111 (DB1) and DB112 (DB2) for the internally used system function blocks SFB52
(RDREC) and SFB53 (WRREC) must be changed accordingly at the FB inputs
DB_Write and DB_Read.
3.4 Examples
3.4.1 "Read" parameter
In the following example, the parameter P100 (actual position value) must be read by
the drive. The following steps are necessary:
1. First FB invocation: Preconfigure all FB inputs Write, Read, Save and
Factory_default with FALSE.
2. Next FB invocation: Query FB output Done to FALSE, then at FB input write
Number=100 and Index=0 and execute instruction via FB input Read to
value TRUE.
3. While instruction processing is running, call module cyclically and query FB
output Done until value is TRUE. The instruction is then complete. In order to
ensure that the value is valid, it must also be checked that the FB output
Error is at the value FALSE. The read parameter value can then be taken
from the FB parameter Value.
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