Rockwell Automation Inc. has rejected a takeover bid by Emerson Electric Co. worth roughly $27.5 billion, spurning a deal that would have combined two big U.S. makers of machines and software used in manufacturing.

The latest half-cash, half-stock bid by Emerson, a St. Louis-based industrial conglomerate, came in early October and was valued at $215 a share, according to Rockwell. The Milwaukee-based maker of industrial equipment said it also rejected an earlier Emerson bid in August valued at $200 a share.

Rockwell Chief Executive Blake Moret said in a statement the company’s board and management are committed to serving the best interests of the company and shareholders and were “confident in the company’s strategic direction and our ability to continue delivering superior levels of growth and value creation.”

An Emerson spokesman on Tuesday confirmed the company’s attempt to acquire Rockwell but declined to comment further.

Rockwell shares surged on news of Emerson’s bids, which had been earlier reported by CNBC. Rockwell shares were up more than 8% to $202.71 in midday trading Tuesday. Emerson’s stock was down 2.6%, suggesting its shareholders are less enthusiastic about a potential deal.