摘要:
The present invention provides a method, system and apparatus for providing failsafe detection for a differential receiver. A bus activity signal (11) is activated when receiving a differential data signal of sufficient amplitude to transition through a predetermined threshold. A failsafe signal (620) indicates a low differential voltage condition. A countdown time period commences (85) upon activation of either signal, and a failsafe condition is determined (89) to exist if the failsafe signal is active (87) when the countdown time period expires (86).
摘要:
In sicherheitskritischen Anwendungen, insbesondere für Stellwerkanlagen, werden aus Logistik- und Kostengründen in redundanten Teilschaltungen (11, 12) identische und identisch programmierte Bauelemente (1, 1') eingesetzt. In den Bauelementen (1, 1') befindliche systematische Fehler können dabei zu einem nicht detektierbaren Doppelfehler führen. Zur Detektion von solchen Doppelfehlern werden für identische Bauelemente (1, 1') mehrere identisch programmierte Bereiche (A1, A2, A3, A4) vorgesehen, die jeweilen verschieden (311, 312; 331, 332; 341, 342) an die jeweilige Teilschaltung (11,12) angeschlossen sind. Die Einbettung der Teilschaltungen (11, 12) in die Logikschaltung kann auf verschiedene, örtliche, mechanische und elektrische Weise erfolgen.
摘要:
The invention relates to a threshold value operation circuit which can perform an analogue type threshold value operation, and which can generate an AC signal with a stabilized frequency and duty ratio which is not influenced by input signal level or characteristic changes of the circuit elements and the like. A switching device (SWa) is switched by a switching signal (Sg) from an external AC source, to modulate an input signal (Vi) which is the subject of a threshold value operation. A modulation signal (V1) thereof is level detected by a level detection circuit (10) having a previously set threshold value, and if within a range of a predetermined level, an AC output (Vo) is generated from the level detection circuit (10).
摘要:
A circuit for detecting when a fault condition has occurred includes an input stage (12, 18, 14, 24, 20) responsive to a logic signal supplied to an input of the circuit for providing an output logic signal at an output thereof. An output stage (26), including a pulldown circuit (30, 32), responsive to the output logic signal of the input stage, for providing an output logic signal at an output of the circuit. A fault detection circuit (34, 36) coupled to the output of the input stage and to the output stage for forcing the output of the circuit to a predetermined logic state when the pulldown circuit of the output stage is defective.
摘要:
To ensure the safe operation of an electronic circuit (10, 12), for example an amplitude modulated carrier signal generator (12), an output (13) of the circuit is analysed to prove the presence of predetermined signal characteristics, for example the carrier signal, or a modulation frequency. The predetermined signal alternatively may be superimposed on an input to the electronic circuit and proved subsequently to be present in the output. The output (13) of the circuit (12) is passed or inhibited, according to whether or not the signal characteristics are proved present, by means of an output enable gate (14) which is self-latching providing the output continuous to be proved correct. A start-up circuit (22) delays a possible inhibit for a limited period following initial power connection to the circuit in order that the output can become established.
摘要:
Die Efindung beziehtsich auf eine Schaltungsanordnung zur Speicherung dynamischer logischer Signale, in der eine logische "0" durch eine Impulsfolge und eine logische "1" durch ein statisches Signal definiert sind. Um bei Impulsausfällen während des dynamischen logischen "O"-Signals eine Fehlfunktion der Schaltungsanordnung weitgehend auszuschließen und eine sichere Betriebsweise (fail-safe) zu gewährleisten, ist das Eingangssignal über eine Torschaltung (T) geführt, die von einer Gleichrichterschaltung (GL) mit einem Gleichrichtersignal derart beaufschlagt ist, daß Impulsausfälle in begrenzter Anzahl toleriert werden. Die Erfindung wird angewendet in Reaktorschutzsystemen.
摘要:
(57) There is provided a logic device (2, 12, 13) wherein an alternating input signal having a frequency which is one of two frequencies allotted to two input logical values, respectively, positive logic "1" and negative logic "0", is inputted to the device. An output logical value is decided depending on the determination which frequencies the input frequency coincides with or not, and an alternating output signal having a frequency which corresponds to the output logical value is delivered out of the device. The logic device, even when constituted with semiconductor elements, can have highly reliable fail-safe capability and can be reduced in size and weight.