The DS3146/DS3148/DS31412 (DS314x) devices include all necessary circuitry to frame and format up to 12 separate DS3 or E3 channels. Each framer in these devices is independently configurable to support M23 DS3, C-Bit Parity DS3, or G.751 E3. The framers interface to a variety of line interface units (LIUs), microprocessor buses, and other system components without glue logic. Each DS3/E3 framer has its own HDLC controller, FEAC controller, and BERT, as well as full support for error detection and generation, performance monitoring, and loopbacks.