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TR - ECE - BA - DGB - 0128 - 01
11/20/2018
3.6.1.2 NMT Node / Life guarding services
With the Node/Life guarding a NMT master can detect the failure of a NMT slave
and/or a NMT slave can detect the failure of a NMT master:
Node Guarding and Life Guarding:
With these services a NMT master monitors a NMT slave
At the
Node Guarding
the NMT master requests the state of a NMT slave in regular
intervals. The toggle bit 2
7
in the “Node Guarding Protocol” toggles after each request:
Example:
0x85, 0x05, 0x85 … --> no error
0x85, 0x05, 0x05 … --> error
Additionally if the
Life Guarding
is active, the NMT slave requests the state of a NMT
master in regular intervals, otherwise the slave changes into the PRE-OPERATIONAL
state.
The
NMT
services
for
Node/Live
guarding
use
the
function
code
1110 bin:
COB-ID 0x700+Node ID
.
Index
Description
0x100C
Guard Time [ms]
At termination of the time interval
Life Time = Guard Time x Life Time Factor [ms]
the NMT slave expects a state request by the master.
Guard Time = 0: No monitoring active
Life Time = 0: Life guarding disabled
0x100D
Life Time Factor
Table 5: Parameter for NMT services