Communications Systems Inc. of Minnetonka has laid off 12 employees because of a slowdown in its fiber-optic network connections business.

The layoffs affect about 8 percent of the workers in the Transition Networks business unit, which has 150 employees. It could not be immediately determined where the business unit is located. At the end of April, Communications Systems had 492 employees, including 229 in Minnesota.

In addition, CEO William Schultz is taking over management of the affected Transition Networks business unit. The company could not be reached to comment on how the change affected Seweryn Sadura, who had been the division’s vice president and general manager.

The Transition Networks unit, which makes components for integrating fiber-optic cable into data networks, had a 16 percent decline in sales in the first quarter compared to a year ago due to reduced government spending and a decline in older products, Communications Systems said.

Communications Systems earned $242,359, or 3 cents a share, in the first quarter, on revenue of $27.5 million. Transition Networks accounted for 39 percent of the company’s first-quarter revenue.