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TSYN
TSYN:The synchronization time TSYN is the minimum time during which each
node must detect the idle state on the transmission medium before it is allowed to
accept the start of a call or token frame.
In the asynchronous mode, the Syn-Time is 33 bits.
In the synchronous mode, the Syn-Time can be selected. The valid value is located
in the SYN-Time register and is between 4 and 32 bits.
TRDY
The TRDY ready time is the time that must elapse as an idle phase on the
transmission medium at the responder after receiving the call frame before it is
permitted to send its response/acknowledgment frame. TRDY is selected in the
TRDY register.
7.11.3 Syni-Timer
Description
This timer is used to monitor the transmission medium to determine whether or not
receiver synchronization takes place within the TSYNI time. The timer is reset at
the first activity on the line after the idle time has elapsed and is incremented with
BRCLK . The timer is stopped when the idle timer lapses. The idle timer therefore
controls the syni timer directly. If the idle timer is running, the syni timer is enabled
and vice-versa . If there is a problem on the transmission medium, for example
permanent logical '0' or a permanent alternation between '0'/'1' in the asynchronous
mode or permanent activity in the synchronous mode, the idle timer does not stop
(no synchronization is then possible): The syni timer them increments to the value
TSYNI = 11385 bits or 8672 bits in synchronous transmission and then stops. The
SPC 4-2 them generates the Error-Interrupt Syni-Error.
After a reset, the syni timer (14 bits) is disabled. It is started specifically by
"START-SPC 4-2 = 1" (mode register 1) following initialization.
3 The PNO Guideline PROFIBUS PA Version 1.0 defines T SYN =28...112 bits. This definition, however, includes the preamble and the
delimiters. If, however, the IDLE timer is reset with the XRxA signal, these parts must not be included.
4 The TRDY time defined here corresponds to the "min T SDR " time as defined in DIN 19245 or for PROFIBUS PA. In the synchronous
mode, TRDY=T IFG (interframe gap time).
102
4
3
PROFIBUS Controller SPC 4®-2 LF
C79000-G8976-C157-3
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