Siemens Simatic 6ES7 157-0AD81-0 A0 Series Manual page 29

Parameter assignment for the DP slave
The parameters for the DP slave in the underlying DP master system are assigned
on the S7-400H via the Y link.
User data of the Y link
The DP user data frame of the Y link is dependent on the number of configured PA
slaves. It consists of the data blocks of the configured DP slaves arranged one
next to the other. The data blocks are sorted in ascending order by DP address.
In the event of the failure of a DP slave, the associated input data in the user data
frame of the DP/PA link are reset first. The corresponding information is then
entered in the diagnostic frame.
When the DP slave is restored, the corresponding information is entered into the
diagnostic frame. At almost the same time, the valid input data of the DP slave in
the user data frame of the Y link become available again.
Diagnostics data of the DP slaves
The processing of the diagnostic frames by DP slaves depends on whether the IM
157 is operated as a DPV0 slave or as a DPV1 slave. For details, see Chapter 10.
In STEP 7, the diagnostic frames of the underlying DP slaves can be displayed in
the online view of the HW Config.
Communication links from the programming device/PC to the DP slaves
Up to 10 communication links to DP slaves can be set up simultaneously from a
programming device/PC via the Y link.
Communication links can only be passed from the S7-400H to the underlying DP
master system.
All communication links from the programming device/PC to the DP slaves remain
intact when the active channel is switched over from one IM 157 to another.
DP/PA Link and Y Link Bus Couplings
A5E00193841-01 1
Description of Components
2-9