Profichip VPC3+C - PROFIBUS DP Interface; DP Buffer Structure

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PROFIBUS DP Interface 6

6 PROFIBUS DP Interface

6.1 DP Buffer Structure

The DP_Mode is enabled in the VPC3+C with ‘DP_Mode = 1’ (see Mode

Default SAP: Write and Read data (Data_Exchange)

SAP 53: Sending extended parameter setting data (Set_Ext_Prm)

SAP 55: Changing the Station_Address (Set_Slave_Add)

SAP 56: Reading the inputs (RD_Input)

SAP 57: Reading the outputs (RD_Output)

SAP 58: Control commands to the DP-Slave (Global_Control)

SAP 59: Reading configuration data (Get_Cfg)

SAP 60: Reading diagnosis information (Slave_Diag)

SAP 61: Sending parameter setting data (Set_Prm)

SAP 62: Checking configuration data (Chk_Cfg)

The DP-Slave protocol is completely integrated in the VPC3+C 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 ‘D’ data transfer and one

buffer is assigned to the ‘U’ user. 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+C for

sending. The other Diagnosis-Buffer (U) belongs to the user for

preprocessing new diagnosis data.

VPC3+C User Manual

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