This invention comprises the use of compounds of formula . In one embodiment, the ambulatory medical device include first circuitry controlling infusion of a medicament to the patient by a fluid conduit connectable to the patient and second circuitry controlling communications when an active communication cable is connected to the medical device. The medium feeding unit also includes a plurality of actuators that sense the number of print media on a loading plate, differentially intercept the sensing area of the sensor thus changing the voltage level of the sensing signal, and therefore signal the medium feeding unit when the number of print media on the loading plate falls below the predetermined remaining number. The isolation assembly is disposed so as to function in parallel to the travel limiter.