A transmitter (12; 100; 200) configured to couple to a process control loop, to sense a process variable using a sensor and to transmit the sensed process variable over the process control loop, wherein the transmitter comprises: a plurality of components; and a supervisory overlayer configured to upgrade the transmitter to meet a desired Safety Integrity Level, SIL, and comprising: a device interface configured to couple to the transmitter and to provide an output related to operation of a monitored component of the plurality of components of the transmitter, the device interface comprising a connection to a databus (282, 284) of the transmitter which is used to transfer data between the plurality of components contained within the transmitter; a component monitor configured to monitor data carried on the databus, to monitor operation of the monitored component based upon the output from the device interface, and to identify a safety event of the monitored component indicative of a failure of the monitored component and provide a safety event output; and a safety response module configured to receive the safety event output and to respond to the safety event of the monitored component in accordance with a safety response; and wherein software and circuitry associated with the supervisory overlayer are completely isolated from the plurality of components of the transmitter to provide additional redundancy. a plurality of components; and a supervisory overlayer configured to upgrade the transmitter to meet a desired Safety Integrity Level, SIL, and comprising: a device interface configured to couple to the transmitter and to provide an output related to operation of a monitored component of the plurality of components of the transmitter, the device interface comprising a connection to a databus (282, 284) of the transmitter which is used to transfer data between the plurality of components contained within the transmitter; a component monitor configured to monitor data carried on the databus, to monitor operation of the monitored component based upon the output from the device interface, and to identify a safety event of the monitored component indicative of a failure of the monitored component and provide a safety event output; and a safety response module configured to receive the safety event output and to respond to the safety event of the monitored component in accordance with a safety response; and wherein software and circuitry associated with the supervisory overlayer are completely isolated from the plurality of components of the transmitter to provide additional redundancy. a device interface configured to couple to the transmitter and to provide an output related to operation of a monitored component of the plurality of components of the transmitter, the device interface comprising a connection to a databus (282, 284) of the transmitter which is used to transfer data between the plurality of components contained within the transmitter; a component monitor configured to monitor data carried on the databus, to monitor operation of the monitored component based upon the output from the device interface, and to identify a safety event of the monitored component indicative of a failure of the monitored component and provide a safety event output; and a safety response module configured to receive the safety event output and to respond to the safety event of the monitored component in accordance with a safety response; and wherein software and circuitry associated with the supervisory overlayer are completely isolated from the plurality of components of the transmitter to provide additional redundancy.