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Fieldbus coupler/controller
Review
L
ON
W
ORKS
®
3.2.6.1 Memory areas
The controller uses a memory space of 256 words (word 0 ... 255) for the
physical input and output data.
Attention
The physical I/O module data can only be read internal by the CPU. The data
must be copyed into the PFC variables via the IEC 61131-3 program, in order
to be processed by the Neuron-Chip and accessed from the fieldbus side.
The controller is assigned an additional memory space for mapping the PFC
variables defined according to IEC 61131-3. This extended memory space
(word 256 ... 511 each) is used to map the PFC variables behind the physical
process image.
CPU
I
O
1
3
1
3
2
4
memory area
for I/O module
input data
memory area
for input
variable data
memory area
for output
variable data
I/O modules
input
modules
word 255
output
modules
word 0
word 255
word 0
memory area
for I/O module
output data
Programmable fieldbus controller
IEC 61131
program
PFC
input
variables
PFC
output
variables
word 256
word 511
word 511
word 256
fieldbus
nvi
nvo
Fig. 3-5: Memory areas and data exchange for a fieldbus controller
g012753e
1
The data of the input modules can only be read internal by the CPU. Via
the IEC 61131-3 program they can be processed or directly copyed on PFC
output variables.
2
In the same manner, writing to the output modules is only possible from
the CPU.
3
Transferring data from the fieldbus side to the controller is made using net-
work input variables (nivs). These are either processed in the Neuron-Chip
via the Neuron-C application or directly transmitted and written to the
memory area of the PFC input variables via the Dual-Port-RAM.
Subsequently the data can be read by the CPU in order to be processed.
4
Once the data has been processed through the IEC 61131-3 program, the
CPU writes the variable data to the memory area of the PFC output
variables.
The variables are transferred to the Neuron-Chip via the DPRAM and
processed in the Neuron-C application. Subsequently the data can be
accessed from the fieldbus side using network output variables (nvos).