Profibus Dp Interface; Dp Buffer Structure - Profichip VPC3+S User Manual

6.1

DP Buffer Structure

The DP_Mode is enabled in the VPC3+S with 'DP_Mode = 1' (see Mode
Register 0). In this mode, the following SAPs are permanently reserved:
Default SAP: Write and Read data (Data_Exchange)
SAP 53:
SAP 55:
SAP 56:
SAP 57:
SAP 58:
SAP 59:
SAP 60:
SAP 61:
SAP 62:
The DP-Slave protocol is completely integrated in the VPC3+S and is
handled independently. The user must correspondingly parameterize the
ASIC and process and acknowledge received messages. All SAPs are
always enabled except the Default SAP, SAP 56, SAP 57 and SAP 58. The
remaining SAPs are not enabled until the DP_SM goes into the DATA-
EXCH state. The user can disable SAP 55 to not permit changing the
Station_Address. The corresponding buffer pointer R_SSA_Buf_Ptr must
be set to '00H' for this purpose.
The DP_SAP Buffer Structure is shown in Figure 6-1. The user configures
all buffers (length and buffer start) in the Offline state. During operation, the
buffer configuration must not be changed, except for the length of the Dout-
/Din-Buffers.
The user may still adapt these buffers in the WAIT-CFG state after the con-
figuration telegram (Chk_Cfg). Only the same configuration may be
accepted in the DATA-EXCH state.
The buffer structure is divided into the data buffers, Diagnosis-Buffers and
the control buffers. Both the output data and the input data have three
buffers available with the same length. These buffers are working as
changing buffers. One buffer is assigned to the data transfer (D) and one
buffer is assigned to the user (U). The third buffer is either in a next state
(N) or a free state (F). One of the two states is always unoccupied.
For diagnosis two Diagnosis-Buffers, that can have different lengths, are
available. One Diagnosis-Buffer (D) is always assigned to the VPC3+S for
sending. The other Diagnosis-Buffer (U) belongs to the user for
preprocessing new diagnosis data.
VPC3+S User Manual
Copyright © profichip GmbH, 2012
PROFIBUS DP Extensions
Sending extended parameter setting data (Set_Ext_Prm)
Changing the Station_Address (Set_Slave_Add)
Reading the inputs (RD_Input)
Reading the outputs (RD_Output)
Control commands to the DP-Slave (Global_Control)
Reading configuration data (Get_Cfg)
Reading diagnosis information (Slave_Diag)
Sending parameter setting data (Set_Prm)
Checking configuration data (Chk_Cfg)
Revision 1.04
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PROFIBUS DP Interface

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