Process interfacing via an automation system (PLC, PC)
10.4 Control with FB79
SIMATIC MV420 / SIMATIC MV440
Operating Instructions, 04/2013, A5E02371045-06
277
10.4.3 Programming data fragmentation
Handshaking
The following sections introduce a handshaking procedure that ensures the consistency of
all the data transferred from the reader to the I/O controller regardless of any configured
consistency mechanisms in PROFINET. This procedure must be used with every data
transfer, even if the transfer only consists of one data block, for example when reading out
the program number selected on the reader.
Remember that you need to enter the required data ID in byte 4 of the "Receive" user data
interface.
Note
Handshaking can only run on the following S7 CPUs
Handshaking using the method described here is only possible on the following S7-CPUs:
• On a CPU 318 and the S7-400 CPUs as of firmware version V3.0.0
• On S7-300 CPUs with MMC
On all other S7-300 and S7-400 CPUs, you must use SFCs 14 and 15 for all access to the
two user data interfaces.
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