Conditions for source and destination field
The source and destination field must not overlap.
If the preassigned destination field is not a whole multiple of the length of the input parameter BVAL, the destination field will nevertheless be written to up to the last byte.
If the specified destination field is smaller than the source field, only the amount of data that can be entered in the destination field will be copied.
If the real existing destination or source field is smaller than the size of the memory area for source or destination field as set in the parameters (BVAL, BLK), the behavior depends on the CPU type:
· S7-300 CPUs: No data is transferred. RET_VAL has the value W#16#837F.
· The following applies to the S7-400 V4 CPUs (standard CPUs V4, H-CPUs V4 and V4.5): No data is transferred.
The following applies to all other S7-400 CPUs: Data is transferred.
With all S7-400 CPUs, an error is shown in RET_VAL with the error code W#16#8122 or W#16#8323. Make sure that you always evaluate these RET_VALs in your user program.
If the ANY pointer (source or destination) is of the type BOOL, the specified length must be divisible by 8 otherwise the SFC will not execute.
If the destination field is of the data type STRING, SFC21 "FILL" writes the entire string including the management information.