Siemens SPC3 - Manual (Page 38)

PROFIBUS Interface Center SPC3
Page 36 V1.3 SPC3 Hardware Description
2003/04 Copyright (C) Siemens AG 2003. All rights reserved.
Bit
Designation Significance
0 Reserved
1 Clear_Data With this command, the output data is deleted in ‘D’ and is changed
to ‘N.’
2 Unfreeze With „Unfreeze,“ freezing input data is cancelled.
3 Freeze The input data is fetched from ‘N’ to ‘D’ and „frozen“. New input data
is not fetched again until the master sends the next ‘Freeze’
command.
4 Unsync The „Unsync“ command cancels the „Sync“ command.
5 Sync The output data transferred with a WRITE_READ_DATA telegram is
changed from ‘D’ to ‘N.’ The following transferred output data is kept
in ‘D’ until the next ‘Sync’ command is given.
6,7 Reserved The „Reserved“ designation specifies that these bits are reserved for
future function expansions.
Figure 6.15: Data Format for the Global_Control Telegram
If the Control_Comand byte changed at the last received Global_Control telegram, SPC3 additionally
generates the ‘New_GC_Command’ interrupt. During initialization, SPC3 presets the ‘R_GC_Command’
RAM cell with 00H. The user can read and evaluate this cell.
So that Sync and Freeze can be carried out, these functions must be enabled in the mode register.
6.2.7 Read_Inputs (SAP56)
SPC3 fetches the input data like it does for the Write_Read_Data Telegram. Prior to sending, ‘N’ is shifted
to ‘D,’ if new input data are available in ‘N.’ For ‘Diag.Freeze_Mode = 1,’ there is no buffer change.
6.2.8 Read_Outputs (SAP57)
SPC3 fetches the output data from the Dout buffer in ‘U’. The user must preset the output data with ‘0’
during start-up so that no invalid data can be sent here. If there is a buffer change from ‘N’ to ‘U’ (through
the Next_Dout_Buffer_Cmd) between the first call-up and the repetition, the new output data is sent during
the repetition.
6.2.9 Get_Config (SAP59)
The user makes the configuration data available in the Read_Cfg buffer. For a change in the configuration
after the Check_Config telegram, the user writes the changed data in the Cfg buffer, sets
‘EN_Change_Cfg_buffer = 1’ (see Mode-Register1), and SPC3 then exchanges the Cfg buffer for the
Read_Cfg buffer. (See Section 3.2.3.) If there is a change in the configuration data (for example, for the
modular DP systems) during operation, the user must return with ‘Go Offline’ (see Mode Register1) to
‘Wait_Prm’ to SPC3.