
Digitax HD M753 Control User Guide
99
Issue Number: 3
9.11
Process Data Objects (PDOs)
Cyclic data is implemented on EtherCAT networks by using "Process
Data Objects" or PDOs. Separate data objects are used for transmitting
(TxPDOs) and receiving (RxPDOs) data. PDO configuration objects are
usually pre-configured in the EtherCAT master controller and
downloaded to the EtherCAT interface at network Initialization using
SDOs.
9.12
Service Data Object (SDO) parameter
access
The service data object (SDO) provides access to all objects in the
EtherCAT object dictionary and the drive parameters are mapped into
the object dictionary as 0x2XXX objects in the following way:
Index: (0x100 x S) + menu number
Sub-index: 0x00 + parameter number
For example Pr
20.021
would be index 0x2014 and the sub-index would
be 0x15. The values are usually expressed in base 16 (hexadecimal),
so care must be taken to enter the correct parameter number.
All other supported entries in the EtherCAT interface object dictionary
can also be accessed using SDOs. Refer to the master controller
documentation for full details about implementing SDO transfers within
the particular master controller.
Bit parameter mapping
When mapping to drive bit parameters, the parameter is stored in the
drive as an 8-bit value, therefore for correct operation, the data type
SINT (short integer) should be used for mapping to these parameters.
The following table shows the drive bit parameter value for a given value
in the EtherCAT master.
This is contrary to other option modules where any value other than zero
will result in the parameter being set to a 1 (On).
Sub-index 0 for any menu will return the highest sub-index available for
the object (i.e. the highest parameter number).
The following SDO services are supported:
•
Initiate SDO Download (Write)
•
Initiate SDO Upload (Read)
•
Abort SDO Transfer (Error)
9.13
CANopen over EtherCAT (CoE)
The CoE protocol over EtherCAT uses a modified form of the CANopen
object dictionary. This is specified in Table 9-5
.
Table 9-5 CoE object dictionary
The object description format describes object related information such
as size, range and descriptions and is detailed in Table 9-6
.
Table 9-6 Object description format
For entries having sub-indices
Table 9-7 Object description format with sub-indices
Definitions:
•
<index>: A signed 16-bit number. This is the index of the object
dictionary entry specified in four hexadecimal characters.
•
<access>: A value describing how the object may be accessed
(RW = read/write, RO = read-only and WO = write-only).
•
<size>: The size of the object/sub-index in bytes.
•
<unit>: The physical unit (e.g. ms, counts per second etc.).
•
<type>: Data type:-
EtherCAT Value
Parameter Value
Decimal
Hex (0x)
-128 to 0
80 to 00
0 (Off)
1 to 127
01 to 7F
1 (On)
Index
Object dictionary area
0x0000 to 0x0FFF
Data type area
0x1000 to 0x1FFF
CoE communication area
0x2000 to 0x5FFF
Manufacturer specific area
0x6000 to 0x9FFF
Profile area
0xA000 to 0xFFFF
Reserved area
NOTE
NOTE
NOTE
<index>
<object name>
Sub-index 0
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
<index>
<object name>
Sub-index 0
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
Sub-index 1
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
Sub-index …
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
Sub-index n-1
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
Sub-index n
Access: <access>
Range: <range> Size: <size>
Unit: <unit>
Default: <default>
Type:
<type>
Description: <description>
Data type
Size (bytes)
Range
Description
USINT
1
0 to 255
Unsigned short integer
SINT
1
-128 to 127
Signed short integer
UINT
2
0 to 65535
Unsigned integer
INT
2
-32768 to 32767 Signed integer
UDINT
4
0 to 2
32
Unsigned double integer
DINT
4
-2
31
to 2
31
-1
Signed double integer
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