ERN Series rotary encoders from Heidenhain Corp., Schaumburg, Ill., can be used with electrical drives in addition to digital drives. ERN 1321 is for asynchronous drives with control that does not require commutation information. It is mounting compatible with the ERN 1381 and supplies incremental square-wave output signals with TTL levels. A fault-detection signal is also output for evaluation in sub-sequent electronics. Electrical connection is made through a 12-pin PCB connector. ERN 1326 is for synchronous drives and supplies three additional signals I, II, and III from the block-commutation tracks, as well as their inverted signals. Block-commutation signals also have TTL levels. Electrical connection is made through a 16-pin PCB connector. Both encoders can be used in applications up to 120°C.