5. Access Procedure
Festo P.BE-CMMP-CO-SW-EN 0708NH
51
5.9.2
Structure of the Nodeguarding messages
A request by the Master must be sent as a so-called remote frame with the identifier
700
h
+ node number
. For a remote frame, a special bit is also set in the
telegram, the remote
bit. Remote frames have no data.
Identifier:700
h
+
node number
701
h
R
0
The regulator's response is structured almost identically to the Heartbeat message.
It contains only 1 byte of reference data, the toggle bit and NMT status of the regulator
(see chapter 5.6).
Identifier:700
h
+
node number
Toggle bit / NMT status
701
h
1
T/N
Data length
The first data byte (
T/N
) is structured as follows:
Bit
Value
Name
Meaning
7
80
h
toggle_bit
Changes with each telegram
0 ... 6 7F
h
nmt_state
04
h
Stopped
05
h
Operational
7F
h
Pre-Operational
The monitoring time for requests by the Master is programmable. Monitoring begins with
the Master's first remote request received. Starting at this time, the remote inquiries must
arrive before the set monitoring time expires, or error 12-4 is triggered.
The toggle bit is reset by the NMT command
Reset Communication
. It is therefore deleted
in the first response of the controller.
5.9.3
Description of the Objects
5.9.3.1 Object 100C
h
: guard_time
For activation of Nodeguarding monitoring, the maximum time between two remote
inquiries of the Master is parameterised. This time is determined in the controller from the
product of
guard_time
(
100Ch
) and
life_time_factor
(
100Dh
). It is thus recommended to
write 1 into
life_time_factor
and then specify the time in milliseconds directly via the
guard_time
.
Remote bit (remote frames have no data)
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