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User manual SCAIME:
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564F
sensor signal outside of the input signal range
5054
CAN transmitter in error passive state
5052
CAN receiver in error passive state
The error register value is also part of the emergency telegram so as to indicate if other internal errors have been
detected.
The number of reported errors is given by an error counter in the
pre-defined error field
located at index 1003
H
, sub-
index 00
h
and the last reported error can be read from the same entry at sub-index 01
H
.
5.6
Error control services
CANopen® uses smart mechanisms to control permanently the nodes state on the bus.
eNod4
supports
Boot-up
and
Heartbeat
messages and
Node guarding protocol
. Using both services is not allowed. If both are configured so as to
be functional, only the Heartbeat mechanism is used.
5.6.1
Heartbeat and boot-up
eNod4
state control can be achieved through the use of Heartbeat and boot-up mechanisms :
Boot-up
: this message sent by
eNod4
means that its initialization phase is complete and that the
node has entered into
pre-operational
state. It consists in the following frame :
Heartbeat
:
- producer mode
: if a Heartbeat period (in ms) different from 0 is set in the entry
‘producer
heartbeat time’
of the object dictionary,
eNod4
generates at this period a frame containing its state
coded on one byte. The corresponding frame is similar to the
Boot-up
mechanism frame:
eNod4
NMT state byte
can take the different following values :
04
H
: the node is in the
«stopped»
state
05
H
: the node is in the
«operational»
state
7F
H
: the node is in the
«pre-operational»
state
Using Heartbeat protocol allows a NMT master to check that all nodes connected to the bus are working correctly.
- Consumer mode
:
eNod4
also can be configured so as to monitor the NMT state of one particular
node of the network (generally the NMT master). The node ID and a period are defined in the entry
‘consumer heartbeat time’
of the object dictionary
If corresponding heartbeat is not received within this time, then
eNod4
sends an emergency
telegram and switches to pre-operational state.
5.6.2
Node guarding
Node guarding protocol is another way to check the nodes state. But unlike Heartbeat protocol, it needs requests
from a NMT master. In this case, the NMT master sends periodically a remote transmit request (remote frame) to the
node with
COB-ID 700
H
+
ID
eNod4
.
eNod4
has to respond by sending a single-byte data frame with its coded state.
This frame is similar to Heartbeat frame but there is an important difference. Most significant bit of the state byte is a
toggle-bit. The value of this bit must alternate between two consecutive responses from the NMT slave. The value of
the toggle-bit of the first response after the Guarding Protocol becomes active is 0.
It is only reset to 0 when a
‘reset communications’
or a
‘reset node’
command is received. If two consecutive
responses have the same value of the toggle-bit, then the new response should be handled as if it was not received by
the NMT master.
COB-ID
DLC
byte 1
700
H
+ ID eNod4
1
0
COB-ID
DLC
byte 1
700
H
+ ID eNod4
1
eNod4
NMT state
