PROFIBUS Controller SPC 4®-2 LF
98
C79000-G8976-C157-3
7.10 Clock
Synchronization
Description
Clock synchronization is triggered by a global control frame (SD2 to SAP58). The
SPC 4-2 handles all global control frames like the SPC 4-1. In addition, however,
when the GCT is error-free, it compares the station address contained in the frame
with a station address set in the internal RAM (test for valid constant-time scan
master). It also compares the group byte in the frame with a group address that is
also set in the internal RAM. If both of these match, a counter is clocked. If the
counter reaches the end value set in the new "Counter end value" register, the
counter is cleared and the MEM-OVERFLOW interrupt is activated. The SPC 4-2
has a new register for the counter end value (address 0x31F, write only)
Bit 5 of the status register (Early-Ready) is used to distinguish between an actual
memory overflow and the clock synchronization event: the interrupt is a clock
synchronization only when this bit is set to 1. The previous function of the Early-
Ready bit is therefore no longer available in the SPC 4-2 mode. The interrupt
register bit TAKT_SYNC (available only internally) is switched to the SPC 4-2
output XINTCI without masking and remains active (zero-active) until the software
clears the interrupt. XINTCI is therefore a new, non-maskable interrupt output.
To activate clock synchronization, the "Enable-SPC 4-2" bit must be set in mode
register 4, only then is access to the three new registers possible. The "Enable-
Takt-Sync" bit must also be set in mode register 4. This activates the new
microprogram section and connects the XINTCI output with the interrupt.
The station address of the valid constant scan time master is stored in the RAM
parameter block at address 0x006. The group-select byte is stored in the ram
parameter block at address 0x007. As a result, the monitoring range of the write
violation interrupt in the SPC 4-2-mode changes by two byte addresses (previously
RAM address 6 to 23
dec
, now 8 to 23
dec)
.
The clock synchronization output XINTCI of the SPC 4-2 is active when a clock
synchronization event occurs at the earliest
delay-min
and at the latest T
delay-max
after
the end of the frame (end of the end delimiter in PA or end of the stop bit in DP).
The difference between T
delay-max
and T
delay-min
is known as jitter. In the PA mode,
both delay times depend on the GCT frame length used, LE = 6 and LE = 7 are
possible.
T
bit
is the period of the baud rate used.
T
spc4
is the period of the SPC 4-2 input clock.
Содержание SIMATIC NET SPC 4-2 LF
Страница 9: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 9 Introduction 1 ...
Страница 11: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 11 Functional Overview 2 ...
Страница 14: ...PROFIBUS Controller SPC 4 2 LF 14 C79000 G8976 C157 3 ...
Страница 15: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 15 Pin Assignment 3 ...
Страница 18: ...PROFIBUS Controller SPC 4 2 LF 18 C79000 G8976 C157 3 ...
Страница 19: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 19 Memory Assignment 4 ...
Страница 32: ...PROFIBUS Controller SPC 4 2 LF 32 C79000 G8976 C157 3 ...
Страница 33: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 33 FLC Interface 5 ...
Страница 50: ...PROFIBUS Controller SPC 4 2 LF 50 C79000 G8976 C157 3 ...
Страница 51: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 51 DP Interface 6 ...
Страница 63: ...ASIC Interface PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 63 ASIC Interface 7 ...
Страница 107: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 107 Asynchronous Interface 8 ...
Страница 114: ...PROFIBUS Controller SPC 4 2 LF 114 C79000 G8976 C157 3 ...
Страница 115: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 115 Synchronous Interface 9 ...
Страница 125: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 125 Clock Pulses 10 ...
Страница 128: ...PROFIBUS Controller SPC 4 2 LF 128 C79000 G8976 C157 3 ...
Страница 129: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 129 Processor Interface 11 ...
Страница 152: ...PROFIBUS Controller SPC 4 2 LF 152 C79000 G8976 C157 3 ...
Страница 153: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 153 Technical Specifications 12 ...
Страница 159: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 159 Package 13 ...
Страница 165: ...Package PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 165 Figure 13 4 Tray Spezification ...
Страница 166: ...PROFIBUS Controller SPC 4 2 LF 166 C79000 G8976 C157 3 ...
Страница 168: ...PROFIBUS Controller SPC 4 2 LF 168 C79000 G8976 C157 3 ...
Страница 169: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 169 Addresses 15 ...
Страница 172: ...PROFIBUS Controller SPC 4 2 LF 172 C79000 G8976 C157 3 ...
Страница 173: ...PROFIBUS Controller SPC 4 2 LF C79000 G8976 C157 3 173 Appendix 16 ...
Страница 178: ...PROFIBUS Controller SPC 4 2 LF 178 C79000 G8976 C157 3 ...