A fail-safe drug infusion system, including a user interface controller (UIC) and at least one pump motor controller (PMC), with protocols that enable the PMC to operate therapy delivery for a limited amount of time if the UIC fails or the communication link between the UIC and the PMC is interrupted. Includes synchronization methods to synchronize the delivery information back to the UIC after the UIC reboots or after the communication link is restored. The PMC may apply intelligent fail-safe drug infusion therapy by temporarily displaying therapy information, for example information normally displayed by the UIC, while taking control of alarm signaling and providing minimal user control of the therapy until the UIC restores itself, the infusion completes normally, or the user stops the infusion. If the PMC becomes inoperable, the UIC may wait for the PMC to reboot, or attempt to switch infusion channels to provide robust drug infusion.