Tactics uses a portserver to manage all communications, which includes Serial connections and IP addressable communications. The serial connections are made using a serial port appliance, like the Comtrol RTS unit. The Tactics Server has a built-in PortServer but on larger systems Siemens recommends adding additional physical servers (i.e. remote portserver) to help offset the load that PortServer communications can generate.
Typically, a serial port appliance is a serial-to-ethernet device that converts a network connection to a Serial Connection (like the 25-pin D-connector on an M40 or M50). The IP address of each of these PortServer’s is configured into Tactics. When the device count gets above 250 Siemens recommends installing an additional physical server to act as a secondary Tactics PortServer.