Table of Contents
Advertisement
●
The received net data length of a DP data frame is less than the indication
buffer length in the DEFAULT SAP:
The SPC 4-2 replies with the input data from reply update buffer D, if
DIAG.FREEZE mode = 0 and RUP-N-Valid = 1, the reply update buffers D and
N are first swapped.
●
The received net data length of a DP data frame is greater than the indication
buffer length in the DEFAULT SAP:
The SPC 4-2 replies with "No-Resource (RR)" and sets the RR flag in the
control byte of the DEFAULT SAP to "logical 1".
The execution time t LM required by the SPC 4-2 for "Leave-Master" depends on
the indication buffer length n and the baud rate:
●
12 Mbauds:
●
For baud rates ≤3 Mbauds :
Notice:
With "Leave-Master", there is a risk that request frames received at the SPC 4-2
during the execution time t
operational during the time t
interrupt is possible.
6.2.6
Baudrate Search
Description
If the "Baudrate-Search" bit is set in mode register 1, the automatic baud rate
search function is active. In this mode, the SPC 4-2 does not evaluate the frames
and simply checks whether or not a frame was received physically error free or not.
To be able to receive reply frames as well, T
regardless of the value set in the SYN-Time register. If the received frame is bad,
the "Wrong-SD" interrupt is generated. If SD4 or a complete SD1/SD2/SD3 frame
is received error free, the "Correct-SD" interrupt is generated. An SC received free
of errors is ignored.
The baud rate to be checked must be set by the FLC.
62
(25 + n) bit clocks < t LM < (30 + 1.5 n) bit clocks
tLM ≈ (20 + n/2) bit clocks
are lost. Since the receiver of the SPC 4-2 is
LM
but cannot be processed, a "FIFO-Overflow"
LM
is reduced to 10 bit times
SYN
PROFIBUS Controller SPC 4®-2 LF
C79000-G8976-C157-3
Advertisement
Table of Contents
