CMGA-E1-CO
12
Festo – GDCP-CMGA-E1-CO-EN – 1201NH
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Can bus termination
It is necessary for CAN to work correctly that both ends of the cabling terminate with a resistor of
120 Ohm.
If the CMGA-E1-CO is at one end of the line and the terminating resistor is not integrated in the plug,
this can be switched with the XB DIP switch.
XB DIP switch
Assigned bus
1
CANopen interface
2
Backplane bus
Tab. 6
XB DIP switch
In the ON position the 120 Ohm resistor is active for the termination.
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Definition of the terms
Term
Meaning
CAN-ID
The CAN identifier, programmed with SafePLC, for the backplane bus communic-
ation of the CMGA basic module. A CMGA uses the CAN protocol 2.0A with 11 bit
address on the backplane bus.
Node ID
A CANopen network consists of maximum 127 subscribers. The Node ID is in this
context the address of the CMGA-E1-CO.
OD
Abbreviation for Object Directory. A CANopen specific term. Each CANopen sub-
scriber has its own object directory as a central data structure.
An entry in the OD is addressed with an index and a sub-index. There are a series
of standard entries and ranges for device-specific information.
SDO
Abbreviation for Service Data Objects. This is a communication alternative for
accessing the OD of a device.
PDO
Abbreviation for Process Data Objects. This communication alternative is quicker
than SDO, but it has some restrictions.
TPDO
The PDOs are divided into RPDOs (= Receive Process Data Objects) and TPDOs
(= Transmit Process Data Objects).
COB-ID
Each CAN telegram has a message identifier. The CAN protocol 2.0A defines a
size of 11 bit, the CAN protocol 2.0B defines a size of 29 bit. The message identi-
fier is named COB-ID with CANopen.
A series of COB-IDs is defined as standard, but there are others which can be
changed.
Heartbeat
A CANopen subscriber with the heartbeat function can produce messages in
cyclical intervals. The heartbeat messages can be used by other subscribers to
monitor the device.
Tab. 7
Terms
