Technical data

Table Of Contents
SFCs for Diagnostics
System Software for S7-300/400 System and Standard Functions - Volume 1/2
A5E00709327-01
13-19
How Do You Call the SFC 87?
The SFC 87 "C_DIAG" offers four possible operating modes which are explained in
the table below.
MODE
(B#16#...)
SFC Copies Connection Data to the User
Program
SFC Transfers Acknowledgement
Information to the Operating System
00 No Yes
01 Yes Yes
02
Yes, if connection data have changed
No, if connection data has not changed
Yes
03 Yes No
The status changes of the connection data since the last call of SFC 87 (with
MODE=B#16#00, 01 or 02) are confirmed by transferring the acknowledgement
information to the operating system.
Note
If you operate SFC 87 in a cyclic interrupt OB in "Conditional Copying" mode
(MODE=B#16#02), you must ensure that no initializing values are contained in the
target area after a cold start of the CPU. You can achieve this in OB 102 with a
single call of SFC 87 in "Unconditional Copying with Acknowledgement" mode
(MODE=B#16#01).