Having a hard time getting IP off 3COM Switch

We have a Cisco Router 2800 hooked up to a 3Com Baseline Switch 2024 which is hooked up to a 3Com Superstack 3 Switch 3250, now we hook up a null modem cable to the 3250 and nothing. I am trying to configure the switch to handle multiple VLANs but can not find out what the IP is of the 3250. Any help out there??? Thanks in advance!