Rockwell will buy Electronics Corp. of America.

Rockwell International said its Allen-Bradley Co. subsidiary will make a $52-per-share tender offer for the Waltham, Mass., manufacturer of photoelectric controls and electronic combustion sensors. The price, equivalent to $99 million for all 1.9 million shares, would represent a $37-million premium over the stock’s closing price Friday of $32.37 1/2, or $61.5 million for all of the shares. The stock jumped Monday to $51.25 a share in reaction to Rockwell’s announcement. Electronics Corp.’s board of directors has unanimously approved a definitive merger agreement.