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Curtis 1352 eXm Manual, R ev. D
PDOs. When the master issues a goto Operational State NMT command, the
eXm will go to full normal operation.
In the Operational state, the eXm will start receiving and responding to
PDOs and process all other necessary CANopen messages.
If the master sends a Stop NMT command or the eXm detects an inter-
nal fault, the eXm will go to the Stopped state. In the Stopped state the eXm
will listen for NMTs and produce its heartbeat message only. PDOs and SDOs
(including any timeouts) are ignored.
At any point, if the master sends a Reset Communication or Reset Mod-
ule (warm boot), the eXm will go to the Initialization state as if there were a
power-cycle.
Baud Rates
The eXm will run at one of five selectable baud rates: 125k, 250k, 500k, 800k,
and 1M. Rates below 125k are not supported.
The baud rate can be changed by an SDO. Changes in the baud rate
require an NMT rest or key-cycle to make the new rate active.
Node Addresses
The node address of the eXm can be 1 to 127 and is used by CANopen to route
messages to the eXm and to denote messages from the eXm. The node address
is part of the COB-ID and therefore also plays a part in message priority and
bus arbitration.
Changes to the node address require an NMT reset or power-cycle.
Standard Message Identiers
The eXm will produce—and respond to—the standard message types with the
following CANopen identifiers.
Message Type Message Identier
NMT 0000 – 00hXx
EMERGENCY 0001 – 01hXx
PDO-TX (MISO) 0011 – 03hXx
PDO-RX (MOSI) 0100 – 04hXx
SDO-TX (MISO) 1011 – 0BhXx
SDO-RX (MOSI) 1100 – 0ChXx
HEARTBEAT 1110 – 0EhXx
The 11-bit identification field is a fixed part of the CANopen specification
called the Communication OBject IDentification (COB-ID). This field is used
for arbitration on the bus. The COB-ID with the lowest value gets priority and
wins arbitration. Consequently, NMT messages have the highest priority of the
standard message types, and the heartbeat has the lowest priority.
3 — CANopen COMMUNICATIONS
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