Copyright © profichip GmbH, 2012
If the user’s evaluation cycle time is shorter than the bus cycle time, the
user does not find any new buffers with the next Next_Dout_Buffer_Cmd in
‘N'. Therefore, the buffer exchange is omitted. At a 12 Mbit/s baud rate, it is
more likely, however, that the user’s evaluation cycle time is larger than the
bus cycle time. This makes new output data available in ‘N’ several times
before the user fetches the next buffer. It is guaranteed, however, that the
user receives the data last received.
For power-on, LEAVE-MASTER and the Global_Control telegram with
‘Clear_Data = 1’, the VPC3+S deletes the ‘D’ buffer and then shifts it to ‘N'.
This also takes place during power-up (entering the WAIT-PRM state). If
the user fetches this buffer, he receives U_Buffer_Cleared during the
Next_Dout_Buffer_Cmd. If the user is supposed to enlarge the output data
buffer after the Chk_Cfg telegram, the user must delete this deviation in the
'N' buffer himself (possible only during the start-up phase in the WAIT-CFG
state).
If ‘Diag.Sync_Mode = 1’, the ‘D’ buffer is filled but not exchanged with the
Data_Exchange telegram. It is exchanged at the next Sync or Unsync
command sent by Global_Control telegram.
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