AM58K CANopen®
6.6 PDO objects
PDO (tx) messages are always made up of 4 CAN Data Bytes and are used by the
encoder to transmit the position value and/or the velocity value.
PDO structure:
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)
velocity value (with PDO4)
PDO1 Cyclic mode
: cyclic transmission
Encoder 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 object
To activate (or deactivate) cyclic mode it is necessary to set to 0 (or 1) the most
significant bit of COB-ID used by PDO1 (object
, sub 1).
PDO2 and PDO3 SYNC mode
: synchronous transmission
Transmission of 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 encoder.
If several nodes (encoders) are connected to the network, the Master receives
the position values from the slaves respecting the Node number order.
The encoder 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 object
, sub 2.
, sub 2.
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 (objects
, sub1).
PDO4 Cyclic mode
: cyclic transmission
Encoder uses the PDO4 message to transmit the velocity value cyclically, i.e.
periodically and independently from the Master.
The interval between two issues is set in the 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 PDO4 (object
sub 1).
NOTE
Several transmission modes can be active at the same time.
MAN AM58K CB E 1.1.odt
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6 - CANopen® interface
