摘要 |
In a prime mover control system, control over the prime mover is dependent, in part, upon the validity of a reference signal to the control system. Circuitry is provided between a reference signal generator and the control system whereby under normal conditions the reference signal to the control system is the same as the output of the reference signal generator. However, if the reference signal generator output becomes invalid, then a stored reference signal may be substituted for the reference signal generator output by switching from a first signal channel to an alternate second signal channel, each channel selectably interconnecting the reference signal generator and the control system. The output of the second signal channel is periodically updated to follow, with a time lag, the reference signal generator output except when an invalid reference signal generator output is detected whereupon the update of the second signal channel is frozen at a last valid reference signal which is then input into the control system. |