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6.2 Description of the DP Services
6.2.1 Set_Slave_Address (SAP55)
6.2.1.1 Sequence for the Set_Slave_Address Utility
The user can disable this utility by setting the 'R_SSA_Puf_Ptr = 00H' buffer pointer. The slave address
must then be determined, for example, by reading a switch, and written in the R_TS_Adr. RAM register.
The user must make a retentive memory possibility available (for example, EEPROM) to support this utility.
It must be possible to store the 'station address' and the 'Real_No_Add_Change' ('True' = FFH) parameter
in this external EEPROM. After each restart caused by a power failure, the user must again make these
values available to SPC3 in the R_TS_Adr und R_Real_No_Add_Change RAM register.
If SAP55 is enabled and the Set_Slave_Address telegram is correctly accepted, SPC3 enters all net data in
the Aux-Puffer1/2, exchanges the Aux buffer1/2 for the SSA buffer, stores the entered data length in
'R_Len_SSA_Data', generates the 'New_SSA_Data' interrupt and internally stores the new 'station address'
and the new 'Real_No_Add_Change' parameter.
parameter to SPC3 again.
'SSA_Puffer_Free_Cmd' (read operation on address 14H). This makes SPC3 again ready to receive an
additional Set Slave Address telegram (such as from another master).
SPC3 reacts independently when there are errors.
Address
Control
7
6
Register
14H
0
0
Figure 6.3: Coding SSA_Buffer_Free_Cmd
6.2.1.2 Structure of the Set_Slave_Address Telegram
The net data are stored as follows in the SSA buffer:
Byte
7
6
5
0
1
2
3
4-243
Figure 6.4: Data Format for the Set_Slave_Address Telegram
SPC3 Hardware Description
Copyright (C) Siemens AG 2003 All rights reserved.
SPC3
After the user has read the buffer, the user generates the
Bit Position
5
4
3
2
0
0
0
0
don´t care
Bit Position
4
3
2
1
PROFIBUS Interface Center
The user does not need to transfer this changed
Designation
1
0
0
0
SSA_Puffer_Free_Cmd
Designation
0
New_Slave_Address
Ident_Number_High
Ident_Number_Low
No_Add_Chg
Rem_Slave_Data additional application-
specific data
V1.3
Page 29
2003/04
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