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Profibus interface center, Spc3 – Siemens SPC3 User Manual

Page 30

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PROFIBUS Interface Center

SPC3

Page 28

V1.3

SPC3 Hardware Description

2003/04

Copyright (C) Siemens AG 2003. All rights reserved.


Address

Bit Position

Designation

RAM
Register

7

6

5

4

3

2

0

2AH

0

0

0

0

0

Set_

Slave_

Adr

Check_

Cfg

Set_

Prm

R_Aux_Puf_Sel

X1

X1

X1 See below for coding.

X1 Coding

0

Aux_Buffer1

1

Aux_Buffer2

Figure 6.2: Aux-Buffer Management


The user makes the configuration data (Get_Config) available in the Read_Cfg buffer for reading. The
Read_Cfg buffer must have the same length as the Cfg_buffer.

The Read_Input_Data telegram is operated from the Din buffer in the ‘D state’, and the Read_Output_Data
telegram is operated from the Dout buffer in the ‘U state.’

All buffer pointers are 8-bit segment addresses, because the SPC3 internally has only 8-bit address
registers. For a RAM access, SPC3 adds an 8-bit offset address to the segment address shifted by 3 bits
(result: 11-bit physical address). As regards the buffer start addresses, this results in an 8-byte graunularity
from this specification.