Manuale d’uso - MCM260X - 47
nodes may monitor the status of the NMT master (life guarding): it starts in the NMT slave after
receiving a first node guarding message from the NMT master. It detects errors in the network
interface of the devices: a remote transmission request from the NMT master to a
particular node triggers a response containing the node status.
• Boot-up: an NMT slave transmits a message after the transition from the Initialising status to the
Pre-Operational status.
SDOs are typically used to configure the devices of a CANopen network, while PDOs are used for fast
data transfer. All the CANopen devices should have at least one PDO, all the other communication
objects are optional.
11.1.2 CANopen Pre-defined Connection Set
When a device must respond to a request from the master, a default frame is used. It comprises 11 bits,
with the first 7 bits (LSB) used for the Node-ID (node address, range 1..127, defined by the manufactu-
rer’s specific configurations), and the last 4 bits (MSB) used for the Function Code.
10
MSB
Function code Node-ID
LSB
9 8 7 6 5 4 3 2 1
Pre-defined connection set defines 4 Rx PDO, 4 TX PDO, 1 SDO, 1 Emergency Object and 1 Node-Er-
ror-Control Identifier. It also supports the transmission in broadcast of NMT Module Control Services,
SYNC and Time Stamp objects. The complete CAN identifier assignment scheme is shown below:
11.1.2.a Broadcast objects of the CANopen Pre-defined Connection Set
Object
Function Code
(bit 7...10)
COB-ID Communication parameters
NMT Module Control 0000 0x000 -
SYNC 0001 0x080 0x1005, 0x1006, 0x1007
Time Stamp 0010 0x100 0x1012, 0x1013
11.1.2.b Peer-to-Peer objects of the CANopen Pre-defined Connection Set
Object
Function Code (bit
7...10)
COB-ID Communication parameters
Emergency 0000 0x81 – 0xFF 0x1024, 0x1015
PDO1 (transmitted) 0011 0x181 – 0x1FF 0x1800
PDO1 (received) 0100 0x201 – 0x27F 0x1400
PDO2 (transmitted) 0101 0x281 – 0x2FF 0x1801
PDO2 (received) 0110 0x301 – 0x37F 0x1401
PDO3 (transmitted) 0111 0x381 – 0x3FF 0x1802
PDO3 (received) 1000 0x401 – 0x47F 0x1402
PDO4 (transmitted) 1001 0x481 – 0x4FF 0x1803
PDO4 (received) 1010 0x501 – 0x57F 0x1403
SDO (transmitted/received) 1011 0x581 – 0x5FF 0x1200
SDO (received/client) 1100 0x601 – 0x67F 0x1200
NMT Error Control 1110 0x701 – 0x77F 0x1016, 0x1017
All the peer-to-peer identifiers are different; as a result, only one master device can communicate with
each slave node (up to 127 nodes). Two slaves cannot communicate because they do not know the
node-ID of the other, only the master knows them.
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