Operation of the DP/PA Link and the Y Link
8-3
DP/PA Link and Y Link Bus Couplings
A5E00193841-011
Yes
The IM 157 enters the DP data cycle and is configured by the DP master.
Power-up of the IM 157
(schematic)
Power on at the IM 157
Bit x+43.0 = 1 in diagnostic frame,
i. e. the start-up delay of the IM 157 is active.
PROFIBUS-PA: IM 157 reads (as far as possible) the PA input data.
PA output data are set to ”0” (CLEAR).
Missing slaves are read in with a ”0”.
All slaves in the data cycle (bit
x+43.1=“1” in the diagnostic frame) or
start-up delay time elapsed?
No
Bit x+43.0 is set to 0
Configuration:
Start-up if ...
Did the IM 157
involve all slaves in the data cycle during
the power-up delay time?
Actual desired
Actual = desired
Yes
IM 157 reads the PA input data.
PA output data are passed on to the slaves.
Bit x+43.0 = ”1”: start-up delay active
Bit x+43.1 = ”1”: all slaves in data exchange
In S7 operation: x = 100
No
The IM 157 exits the DP and PA data
cycle.
Figure 8-1 Start-up behavior of the IM 157 after power is switched on
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