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In addition, with the MODBUS TCP/IP protocol, all output data has a
mirrored image in memory with the address offset 0x0200 or 0x1000. This
permits reading back output values after they are written by adding 0x0200 or
0x1000 to the MODBUS address.
In addition, the controller offers other memory spaces which partly cannot be
accessed from the fieldbus master:
RAM
Memory
256 kByte
Code-
Memory
512 kByte
NOVRAM
Remanent
Memory
24 kByte
(Retain)
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP
The RAM memory is used to create variables not required for
communication with the interfaces but for internal processing,
such as for instance computation of results.
The IEC 61131-3 program is filed in the code memory. The code
memory is a flash ROM. Once the supply voltage is applied, the
program is transmitted from the flash to the RAM memory.
After a successful start-up, the PFC cycle starts when the
operating mode switch is turned to its upper position or by a
start command from WAGO-I/O-PRO CAA.
The remanent memory is non volatile memory, i.e. all values are
retained following a voltage failure. The memory management is
automatic. This 24 kByte sized memory area (word 0 ... 12288)
devides on into a 8 kByte sized addressable range for the flags
(%MW0... %MW4095) and a 16 kByte sized Retain range for
variables without memory space addressing or variables which
are explicitly defined with "var retain".
Note
The allocation of the NORAM is if necessary changeable in the
programming software WAGO-I/O-PRO CAA/
register: "Ressourcen"/dialog: "Target Settings" (see picture).
The start address for the flag range is thereby firmly addressed
with 16#30000000. The range sizes and the start address of the
Retain memory are variable. To exclude a data overlap of the
ranges, it is however recommended, to maintain the default
settings. Thereby the size of the flag range is given with
16#2000 and subsequently to it the Retain memory has the start
address 16#30002000 and the size of 16#4000.
Fieldbus Controller
Fieldbus Controller 750-872/020-000
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