If you PC is configured to connect to the internet or a corporate network, then you can temporarily change the TCP/IP configuration, via LAN Connection / Properties from the Control Panel. See the Acromag User Manual, "Connecting Acromag Series 900EN Ethernet Modules To Your PC." You will then not be able to connect to the internet or the corporate network.
If you need your PC to communicate with the Acromag module and also be able to go on the Internet or a corporate network, then you will need to install a second network interface card. The PC browser will know to communicate with the module when entering the module's default IP address into the browser's address field.