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3.2. Database: general description
The size of the database of each slave device is fixed and equal to 118 words, as
follows:
•
From master device to slave device
-
Information common to all slave devices (3 words)
-
Local information for the slave device (8 words)
-
Output database for the slave device (48 words – 16 usable with EXP-ETH-
GD-ADV)
•
From slave device to master device
-
Local information about the slave device (11 words)
-
Slave input database (48 words – 16 usable with EXP-ETH-GD-ADV)
The database is exchanged without acknowledgement in the following modes:
-
from master device to slave device (Outputs) in broadcast mode in the syn-
chronisation message
-
from slave device to mater device (Inputs) in the time slot assigned to the
slave device
The master to slave device database is always exchanged, whereas the slave
to master device database can only be exchanged at the request of the master
device, at each scanning cycle (always) or only when some inputs are changed.
(In practice, if the database of a slave device is not requested, none of its inputs
change and no faults are detected, the slave device does not send anything for
that cycle: a watchdog system must therefore be provided, for example the data-
base request by the master device sent to all the slave devices every 10 msec).
Details of setting the timer for input and output information are provided above.
Local information contain an additional access option (direct access) which allows
a word to be read or written at any module or data structure address. Writing
follows the output timing, whereas reading is immediate (upon receipt of the
broadcast message).
3.2.1. Cyclic data exchange
Process data exchanged cyclically between the GDNet master device and the
EXP-ETH-GD-ADV card are contained in the database. The ODB output database
is composed of the data sent by the master device to the slave device: it must be
configured on the drive in the "COMMUNICATION->FIELDBUS M2S" menu.
The IDB input database is composed of the data sent by the slave device to the
master device: it must be configured on the drive in the "COMMUNICATION-
>FIELDBUS S2M" menu.
Configurations performed on the drive must be the same as those on the master
device in terms of the total ODB/IDB size, number of parameters set, the IPA of
each parameter and the dimension with which it is associated. You must restart
the drive to enable settings defined in the "COMMUNICATION->FIELDBUS M2S"
and "COMMUNICATION->FIELDBUS S2M" menus.
If the settings between the master and slave devices are different, the master de-
vice detects a type H fault (see chapter 4). You will need to reconfigure the slave
or master device to remove the fault and enable data to be exchanged.
EN- 22
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