Lika IF55 ROT CB, User Manual, Page: 44 / 88

IF55 ROT CANopen®
6.6 PDO objects
PDO (tx) messages are always made up of 4 CAN Data Bytes and are used by the
unit to transmit the position value.
Structure of PDO objects:
IDENTIFIER 4 CAN Data Bytes
COB-ID(hex) Byte 0 Byte 1 Byte 2 Byte 3
F.C. Node-ID Low … … High
position value (with PDO1, PDO2, PDO3)
Three types of PDO messages are defined, they are:
PDO1 Cyclic mode : cyclic transmission of the position
The device uses the PDO1 message to transmit the position value
cyclically
, i.e.
periodically and independently from the Master.
The interval between two issues is set in the
6200-00 Cyclic timer object.
To activate (or deactivate) the cyclic mode it is necessary to set to 0 (or 1) the
most significant bit of COB-ID used by PDO1 (
1800 PDO1 parameters
, sub 1
object).
PDO2 and PDO3 SYNC mode : synchronous transmission of the position
The transmission of the position value is managed by the Master
by sending a
SYNC message
.
SYNC message is a high-priority COB transmitted by the Master to request the
position value of the Slave through a PDO.
If several nodes (Slave devices) are connected to the network, the Master
receives the position values from the Slaves according to the order of the Node
addresses.
The unit can be programmed to send a reply after a set number of SYNC
messages by setting a counter.
The PDO message will be transmitted after having received the set number of
SYNC messages.
For PDO2 the value of the counter must be set in the
1801 PDO2 parameters
,
sub 2 object.
For PDO3 refer to the
1802 PDO3 parameters
, sub 2 object.
The SYNC transmission mode can be enabled (or disabled) by setting to 0 (or 1)
the most significant bit (MSB) of COB-IB used by PDO (
1801 PDO2 parameters
/
1802 PDO3 parameters
, sub1 objects).
NOTE
More than one transmission mode can be active at the same time.
MAN IF55 ROT CB E 1.2.odt 6 - CANopen® interface (DS 406) 44 of 88