Abstract: Software driven controller emulator includes hardware apparatus for emulating the controller at a speed faster than the software driven emulator, incorporating predicting a next event to be emulated and preactivating dedicated logic to emulate the controller driving the next event. In case of errors, the hardware controller sets a code signal and returns emulation to the software driven emulator for error recovery identified by the code signal.

Abstract: Programmed controllers execute sequences of control functions for controlling a device. External noise can cause controller malfunctions on critically operated devices. Proper sequencing is verified by assigning access key/check codes to particular sequences. A check key code is generated during execution of a sequence only if the sequence is properly executed by the programmed controller. At completion of the control sequence, the generated code is compared with the access or original code for verifying appropriate programmed controller sequencing. Several sequences can be embedded or nested in each other, each having its own check key with the overall sequence also having an independent check key.