PROFIBUS-DP characteristics
Section 1-4
6
1-4-3
Diagnostics functions
Extensive diagnostics
Device related diagnostics
Module related diagnostics
Channel related diagnostics
The extensive diagnostic functions of PROFIBUS-DP enable fast location of
faults. The diagnostic messages are transmitted over the bus and collected at
the master. These messages are divided into three levels:
•
Device related diagnostics
These messages concern the general operational status of the whole
device (i.e. overtemperature or low voltage).
•
Module related diagnostics
These messages indicate that a fault is present in a specific I/O range
(e.g. an 8-bit output module) of a station.
•
Channel related diagnostics
These messages indicate an error at an individual input or output (e.g.
short circuit on output 5).
1-4-4
Protection mechanisms
Time monitoring
At the master
At the slave
PROFIBUS-DP provides effective protection functions against parameterisa-
tion errors or failure of the transmission equipment. Time monitoring is
provided at the DP master and at the DP slaves. The monitoring interval is
specified during the configuration.
•
Protection mechanism at the master.
The DPM1 monitors data transmission of the slaves with the
Data_Control_Timer. A separate control timer is used for each slave. This
timer expires when correct data transmission does not occur within the
monitoring interval. The user is informed when this happens. If the
automatic error reaction (Auto_clear = TRUE) has been enabled, the
DPM1 exits its Operate state, switches the outputs of all assigned slaves
to fail-safe status and changes to its Clear status (see also next section).
•
Protection mechanism at the slave.
The slave uses the watchdog control to detect failures of the master or the
transmission line. If no data communication with the master occurs within
the watchdog control interval, the slave automatically switches its outputs
to the fail-safe status.
Also, access protection is required for the inputs and outputs of the DP
slaves operating in multi-master systems. This ensures that direct access
Bus cycle time vs number of slaves
0.0
5.0
10.0
15.0
20.0
25.0
0
4
8
12
16
20
24
28
32
Slaves
B
u
s
c
y
c
le
t
im
e
[
m
s
]
500
1500
3000
12000
Conditions:
Each slave has 2 bytes of input data and 2 bytes of output data.
Содержание C200HW-PRM21
Страница 1: ...C200HW PRM21 PROFIBUS DP Master Unit OPERATION MANUAL Cat No W349 E2 2...
Страница 2: ......
Страница 3: ......
Страница 4: ......
Страница 5: ...C200HW PRM21 PROFIBUS DP Master Unit Operation Manual Produced May 2000...
Страница 6: ...iv...
Страница 8: ...vi...
Страница 12: ...x...
Страница 66: ...Debug mode Section 4 4 50...
Страница 98: ...Messages Section 6 4 82...
Страница 108: ...Maintenance Section 7 3 92...
Страница 110: ...94...
Страница 112: ...96...
Страница 116: ...100...
Страница 120: ...104...
Страница 124: ......
Страница 126: ...Authorised Distributor Cat No W349 E2 2 Note Specifications subject to change without notice Printed in the Netherlands...