Technical data

Data exchange using the job buffers of the dual-port RAM
With S5-S5 data transmission and free layer 2 access (refer to Chapters 7
and 8) data is exchanged using the dual-port RAM of the CP 5430 TF/CP
5431 FMS. All data and functions passing through the dual-port RAM of the
CP 5430 TF/CP 5431 FMS must be provided by handling blocks from the
point of view of the control program.
The principle of the PLC-CP link
The interface between CPs and the PLC is a dual-port RAM (DPR) which is
organized in the same way in all S5 CPs. The CP 5430 TF/CP 5431 FMS
has four such DPR interfaces so that in multiprocessor PLCs each central
processing unit (CPU) can communicate with the CP independently of the
others. The STEP 5 user program controls the CP via the DPR using
handling blocks (HDBs). The STEP 5 user cannot access CPs directly
(without using handling blocks). The following system calls (i.e. HDBs) are
available:
➣
SEND transfer data to the CP
➣
RECEIVE receive data from the CP
➣
RESET ALL warm restart on the module
➣
CONTROL request the status of a job
➣
SYNCHRON start up and synchronize the PLC and CP
All these handling blocks must be assigned an interface number and a job
number (SYNCHRON only requires an interface number).
The job number (ANR)
identifies both a task on the CP and in the PLC.
On the CP, the job number also involves a parameter set which defines the
assignment to a virtual circuit, the data direction and the priority class.
Technical Description and Installation of the CP 5430 TF/CP 5431 FMS B8976060/02
Volume 1 4 - 8