Figure 37: Mapping The Process Data - WAGO I/O-SYSTEM 750 Manual

70 Function Description

Figure 37: Mapping the Process Data

The process data are saved in the slave RAM and are represented in the input
area (0x6000..0x6FFF) and output area (0x7000..0x7FFF) in the Object
Dictionary in the slave by corresponding objects.
Internally, this type of object or its subindex refers solely to the location in the
device where the represented data are stored. The objects and their subindices
are generated and named such that they generally reflect the physical structure
of the device and the user can easily understand their meaning.
Entries of objects 0x6000 and 0x7000 can in turn be referenced by so-called Rx
and TxPDO's using their index and subindex. RxPDO's 0x1600 to 0x17FF are
provided for output data, and TxPDO's 0x1A00 to 0x1BFF are provided for input
data. A PDO therefore encapsulates several process data in a type of packet.
The Rx and TxPDO's are listed in the Sync Manager Assignment Lists 0x1C12
(output data) and 0x1C13 (input data). These lists define which Rx/TxPDO's and
in which order the data referenced by the PDO's is to be cyclically transmitted.
Objects 0x6000 and 0x7000 thus specify which input and output data the slave
has. The Rx/TxPDO's group the input and output data into packets and the Sync
Manager Assignment Lists define which packets are cyclically transmitted in
which order.
The EtherCAT
Sync Manager Assignment Lists by the master, as well as read-only status. In
the first case, the user can fully configure the structure of the cyclically
exchanged process data.
However, for most slaves these objects are read-only and all process data must
be cyclically transmitted. The master selects the objects during the slave boot-up
and determines from this the exact structure of the cyclically exchanged process
data. For slaves of this type, the structure of the process data in the RAM is
identical with the structure of the cyclically exchanged data. In this way, the data
can be directly copied internally and do not have to be resorted.
The following figure illustrates the mechanism by means of an example.
The imaginary slave has as its input data two UINT8 "data A" and "data B",
one UINT16 "data C" and two BIT4 "data D" and "data E".
Manual
Version 1.2.1
750-354/000-001 EtherCAT® Fieldbus Coupler, ID Switch

specification enables writing of the Rx/TxPDO's and the Sync
WAGO-I/O-SYSTEM 750