Network Systems Corp, which quietly minded its own business in Minneapolis for many years, is clearly now on the acquisition trail, and following its picking up of Vitalink Communications a couple of years back, it is now moving for Bytex Corp, the Westborough, Massachusetts-based vendor of local and wide area network performance and reliability products. The two have definitive agreement for Network Systems to make a tender offer of $6.80 a share cash, $47m all told, for Bytex. Bytex claims expertise in fault-tolerance, switching and leading edge software design to produce matrix switches and local network switching hubs.