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Above, the data
modules
which HPM-610 supports include: Word integrity, Byte integrity and length
integrity.
For the data modules that support Word and Byte integrity, you can use command “MOVE” to access the
data during STEP7 programing.
For the data
modules
that support length integrity, user can take compression way to send and receive data.
The compression way mainly uses “SFC 15” and receiving uses “SFC 14”
6.2 How STEP7 select data module
Generally, when the
data modules
include “Consistent”, this means this data
module
is
is length integrity,
Take “2 words Input Consistent” as an example, when you choose the module, you must use “SFC 14” access the
data address. When some data of Modbus slave is two-word data, and needs high accuracy and real-time, user
generally select “2 words Input Consistent”, and
not to select “2 words Input”.So, PLC can access the whole
data module during reading data, and it can also prevent data from changing (last word data and next word data
SFC14
SFC15
