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Communication via Function Blocks
Introduction
Communication between the CPU, the CP 440 and a communication partner takes place via
the function blocks and the protocols of the CP 440.
Communication between CPU and CP 440
The function blocks form the software interface between the CPU and the CP 440. They
must be called in cycles from the user program.
Restriction in Multicomputing Operation
In multicomputing operation only one CPU can access the CP because communication
between the CPU and CP is not multicomputing-compatible.
Communication between CP 440 and a Communication Partner
The transmission protocol conversion takes place on the CP 440. The protocol is used to
adpat the interface of the CP 440 to the interface of the communication partner.
This enables you to link an S7 programmable logic controller with any communication
partner that can handle the ASCII driver and the 3964(R) procedure.
Calling the Function Blocks in Interrupt OBs
It is not permissible to simultaneously call a function block in OB1 and in the interrupt OB
(time OBs). The reason for this is that the function block cannot be called again if an interrupt
OB triggers an interruption. If you need to call the function block in OB1 and in the interrupt
OB, you must disable the interrupts (SFC 41) in the lower priority OB before the FB call and
enable them again after the FBs have executed.
Point-to-point connection CP 440 Installation and Parameter Assignment
Manual, 09/2007, A5E00057742-03
www.gkbpx.com
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