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6.3.
PDO (Reading senso r ou tput)
The Process Data Object (PDO) is used to process real time data. The measured values such as inclination,
temperature, etc. are sent with TPDOs. PDOs are transmitted in the NMT operational state only and may be
transmitted when a mapped process data item changes.
The device supports 2 TPDOs. In factory default mode, TPDO1 sends the sensor output, TPDO2 is disabled. The
communication parameters of TPDOs can be configured with object 1800
h
and 1801
h
. The data transmitted with
TPDOs can be configured with TPDO mapping parameters object 1A00
h
and 1A01
h
.
6.4.
SDO (configu ring Object Dictionary )
The Service Data Object (SDO) is used to set and request values from the object dictionary. There are three
types of SDO services used to transmit data. In this context, the device is considered as a server (owner of the
object dictionary) and communication is viewed from the server.
SDO Services
Description
SDO Request
(600
h
+ Node ID)
SDO Response
(580
h
+ Node ID)
SDO upload
Read from device
Server -> Client
40
h
= Expedited Read
43
h
= Read reply 4 bytes
47
h
= Read reply 4 bytes
4B
h
= Read reply 4 bytes
4F
h
= Read reply 4 bytes
SDO download
Write to device
Client -> Server
23
h
= Expedited Write, 4 Bytes
27
h
= Expedited Write, 3 Bytes
2B
h
= Expedited Write, 2 Bytes
2F
h
= Expedited Write, 1 Byte
60
h
= Write Reply
SDO abort transfer
Indicates error
80
h
= Error/Abort code
Table 13 - Expedited SDO transfer command specifier
6.5.
NMT state
CANopen devices are initialized, started, monitored, reset or stopped using NMT services. The NMT state of the
device can be set by applications such as PLC software. The following table shows the communication objects
that exist in each NMT state.
NMT State
PDO
SDO
SYNC
EMCY
Heartbeat
Description
Pre-operational
No
Yes
Yes
Yes
Yes 7F
h
Configuration mode: PDOs do not exist.
This is the recommended mode for
configuration of PDOs.
Operational
Yes
Yes
Yes
Yes
Yes 05
h
Take care with configuration in this mode,
as some objects are protected and may
not be changed in this mode.
Stopped
No
No
No
No
Yes 04
h
All communication is forced to stop
except the heartbeat/node guarding.
Bootup
No
No
No
No
Yes 00
h
Device is initialised with default power-on
values
Table 14
– NMT states and communication objects
