Fault monitor for numerical control system
First Claim
Patent Images
1. In a numerical control system having a plurality of separately operating programmed processors which operate together to control a machine tool, the improvement therein comprising:
- a set of watchdog timer circuits, one associated with each of said processors and each watchdog timer circuit having an input terminal which periodically receives a signal from its associated processor that resets the watchdog timer and each having an output terminal at which a fault indicating logic signal is generated when the watchdog timer is not reset by its associated processor within a preset time interval;
a fault monitor line coupled to the output terminal of each of said watchdog timer circuits; and
an emergency stop circuit coupled to said fault monitor line and being operable to indicate a malfunction condition when any one of said watchdog timer circuits generates a fault indicating logic signal.
0 Assignments
0 Petitions
Accused Products
Abstract
Associated with each processor in a multiprocessor numerical control system is a watchdog timer circuit which is periodically reset by its processor under normal operating conditions. If a malfunction should occur in one of the processors, its watchdog timer is not reset and it times out. A fault monitor line connects to each watchdog timer circuit and an emergency stop circuit, and when a malfunction occurs in any one of the processors, this condition is indicated to all the processors and to the emergency stop circuit.
53 Citations
7 Claims
-
1. In a numerical control system having a plurality of separately operating programmed processors which operate together to control a machine tool, the improvement therein comprising:
-
a set of watchdog timer circuits, one associated with each of said processors and each watchdog timer circuit having an input terminal which periodically receives a signal from its associated processor that resets the watchdog timer and each having an output terminal at which a fault indicating logic signal is generated when the watchdog timer is not reset by its associated processor within a preset time interval; a fault monitor line coupled to the output terminal of each of said watchdog timer circuits; and an emergency stop circuit coupled to said fault monitor line and being operable to indicate a malfunction condition when any one of said watchdog timer circuits generates a fault indicating logic signal. - View Dependent Claims (2, 3, 4)
-
-
5. In a numerical control system having a plurality of separately operating programmed processors which operate together to control a machine tool, the improvement therein comprising:
-
a set of fault detecting circuits, one associated with each of said processors and each fault detecting circuit being operable to generate a fault indicating logic signal at its output when a malfunction in its associated processor is detected; means connecting the output of each fault detecting circuit to an interrupt request terminal on its associated processor; and a fault monitor line coupled to the output terminal of each fault detecting circuit to apply a fault indicating logic signal generated by any one of said fault detecting circuits to the output terminals of all said fault detecting circuits, wherein the generation of a fault indicating logic signal by any one of said fault detecting circuits causes an interrupt request signal to be applied to the interrupt request terminal on each processor in the numerical control system. - View Dependent Claims (6, 7)
-
Specification