SERCON410B Datasheet, PDF (29/34 Pages) STMicroelectronics – SERCOS INTERFACE CONTROLLER

SERCON410B
DATA STRUCTURES WITHIN THE RAM (Continued)
4.2.2 Data Containers
A data container comprises one or two 16-bit con-
trol words as well as a variable number of data
words. If the data is stored in the internal RAM
(DMA = 0) and a single buffer is used (DBUF = 0),
the data container has one buffer. Using RAM
storage and double buffering (DBUF = 1), two data
buffers are needed. In case of DMA transfer (DMA
= 1) the data container only comprises the control
words (Fig. 13). The structure of the two control
words depends on whether a telegram is transmit-
ted or received:
Index
0
1
Bit
0-9
10
11-13
14
15
0-15
Name
LEN
SVFL
NSV
SCMASTER
LASTDC
POS
Function
Number of 16-bit data words of the data block.
Flag, whether data block uses service container (SVFL = 1).
Number of service container, which is used (0 - 7).
Processing of service container in slave mode (SCMASTER = 0)
or master mode (SCMASTER = 1).
Last data container of the telegram (1) or further data containers
follow (0).
Position of the data block within the telegram in number of words.
The first data record of a telegram has POS = 0 (only in case of
receive telegrams).
Figure 13. Structure of Data Containers
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