Systems can include a mobile device, an accessory configured to generate data representative of at least one parameter of a device under test, and an isolated test block comprising at least one input for interfacing with the accessory and an output configured to communicate accessory output data. The mobile device can include a display and be configured to receive the accessory output data from the isolated test block and to present a display based at least on received accessory output data. The accessory output data received by the mobile device can be electrically isolated from the accessory to provide protection to a device user and the mobile device.