Commissioning and configuration
Leuze electronic
MA 235
i
63
TNT
35/7-2
4
V
12.4.2
Object directories
All process data and parameters are stored as objects in the MA 235
i
. The object directory
of the MA 235
i
is the compilation of all process data and parameters of the gateway.
An object directory is structured such that some objects within a device profile are manda-
tory while others are freely definable and stored in the manufacturer-specific object area.
The objects are uniquely identified using an index addressing scheme. The structure of the
object directory, the assignment of the index numbers, as well as some mandatory entries
are specified in the CIA standard DS301 for CANopen.
EDS file
For the user, the object directory of the MA 235
i
is stored as an EDS file (Electronic Data
Sheet).
The EDS file contains all objects with index, sub-index, name, data type, default value,
minimum and maximum, and access privileges. That means the EDS file describes the entire
functionality of the MA 235
i
, and it is possible to adjust both the communication of the
gateway with the control and the RS 232 interface.
Notice!
The size of the input and output data is permanently set for CANopen: the MA 235
i
always
provides the process data for transmission in this form: 8 bytes Tx and 8 bytes Rx.
The EDS file has the name MA 235
i
.eds and is available for download on the Leuze home
page.
Vendor ID for the MA 235
i
The Vendor ID assigned by Leuze electronic for the MA 235
i
is 121
h
= 289
d
.
Detailed information on the device description file and the object directory can be
found in chapter 12.4.6.
12.4.3
SDOs and PDOs
The data exchange in CANopen distinguishes between service data objects (SDOs), which
are used for transmitting the service data (parameters) from and to the object directory, and
process data objects (PDOs), which are used to exchange the current process states.
12.4.4
SDOs
By using SDOs, all entries of the object directory can be accessed. Within one SDO call,
only one object can be accessed at any one time. For this reason, a service data telegram
must have a protocol structure which describes the exact target address by means of
index and sub-index addressing. SDO telegrams place a part of the SDO addressing into
the user data area. Eventually, a user data area with a width of 4 bytes out of the possible
8 bytes of user data remains for each SDO telegram.
The target address always responds to SDO transfers.
In the following, the index and sub-index address of the MA 235
i
parameters and vari-
ables can be found in the individual object descriptions.
