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System 6844(RC) - V03.00
hopf
Elektronik GmbH
Nottebohmstr. 41
• D-58511 Lüdenscheid • Tel.: +49 (0)2351 9386-86 • Fax: +49 (0)2351 9386-93 • Internet: http://www.hopf.com • E-Mail: [email protected]
9.1.4 Send LED
Only Boards for the System-Bus have Send LEDs (see
Chapter 8 Function
Function Boards without a Send LED
Function Boards without a Send LED are supplied with the appropriate time information such
as DCF77 pulse and PPS directly from the Control Board. The output of serial strings is also
possible for this board type (additional system-internal wiring is required).
Function Boards with a Send LED
Function Boards with a Send LED have their own processor. They are provided with infor-
mation via the System-Bus. These boards can prepare this time information and output it in
the respective board-specific form.
9.1.5 Auto-Reset Logic (System-Bus)
The System has circular auto-reset logic. This means that each board inserted into the Sys-
tem-Bus (System-Bus boards only) is integrated into a reset circuit. In the event that:
a board is removed from the System
a board is defective
a Function Board is in an undefined condition (program malfunction)
then this is recognized by the Control Board 6844(RC) and the System triggers a system-
wide hardware-reset.
Bus-Bridge Boards installed in the factory are integrated into the auto-reset circuit and can
be replaced by suitable Function Boards without system-internal modifications.
Auto-Reset Logic Operating Principle
There is a watch-dog module on the Control Board 6844(RC). An output signal transmitted
from the Control Board to the System-Bus must be fed back to this module; otherwise a cy-
clical hardware-reset is triggered on the System-Bus.
This signal is forwarded from one Function Board to the next Function Board on the System-
Bus. The signal is fed back to the Control Board from the last board via a bus termination.
In the event that a fault (e.g. program malfunction) arises on a board or the auto-reset circuit
is broken (board was removed from the System), then the signal is no longer forwarded by
this board and the Control Board triggers a system-wide hardware-reset via the System-Bus.
After this all boards perform a defined program restart.
All boards wi
th their own processor are actively integrated into the System’s auto-reset logic.
On boards without a processor the circulating signal is bridged and by this means the pulse
is forwarded directly to the next board.
