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Table Of Contents
SFCs and SFBs for Updating the Process Image and Processing Bit Fields
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
14-9
14.6 Resetting a Bit Field in the I/O Area with SFC 80
"RSET"
Description
Calling SFC 80 "RSET" (reset range of outputs) has the following effect:
• The bit field in the peripheral I/O area selected with the parameters N and SA is
reset.
• The corresponding bits in the process image output table are also reset
regardless of whether or not they are in a process image section.
The bit field must be located in the part of the peripheral I/O area to which a
process image is assigned.
If no module is plugged in for part of the selected bit field, SFC 80 still attempts to
reset the entire bit field. It then returns the appropriate error information in
RET_VAL.
Note
When SFC 80 is executed, whole bytes are written to the peripheral I/O area.
If the bit field selected with the parameters N and SA does not begin or end at a
byte boundary, calling SFC 80 has the following effect:
• The bits in the first and last bytes to be transferred to the peripheral I/O area
and that do not belong to the selected bit field contain the value of the
corresponding bits in the process image output table. This can lead to
unintended reactions such as starting a motor or turning off a cooling system.
• The bits belonging to the selected bit field are set as explained above.
If you assign the value 0 to the N parameter, calling SFC 80 has no effect. If the
master control relay is not set, calling SFC 80 has no effect.
Parameter Declaration Data Type Memory Area Description
N INPUT INT I, Q, M, D, L, constant Number of bits to be reset
RET_VAL OUTPUT INT I, Q, M, D, L Error information
SA OUTPUT POINTER P Pointer to the first bit to be reset
Error Information
How you evaluate the error information of the parameter RET_VAL is explained in
Evaluating Errors with the Output Parameter RET_VAL. This chapter also contains
the general error information of the SFCs. SFC 80 does not provide any specific
error information with the RET_VAL parameter.