The Mercury4e is an advanced RFID reader module developed for the embedded-reader market, which comprises label printers, label applicators and similar devices. Like other readers in ThingMagic's Mercury family, the Mercury4e is built using software-defined-radio (SDR) architecture making it possible for hardware to read virtually any tag. The architecture provides ThingMagic customers with a single hardware and software platform that can be upgraded via firmware as new tag protocols are introduced. Operating frequency is 902-928 MHz for FHSS use and certification in the U.S. and Canada.

Mercury4e is designed for embedded applications within a host system. It interfaces via asynchronous serial (TTL-level RS-232) using packetized polled-mode communication. In addition, Mercury4e is intended for encoding and verifying transponders, such as RFID tags, in embedded-label printers where distance from antenna to transponder is typically less than four inches. In addition, transponders are singulated so there is no need for anti-collision capabilities, and the protocol used for encoding is known in advance.

Mercury4e readers have a single on-board processor, a TI 55xx series DSP. The reader operates in a single-tasking, streaming mode where tag IDs are sent back to the host processor one-at-a-time, in a mode suitable for small tag populations where reading occurs primarily when triggered by the host system.