Cisco Secure ACS vs. Firewall

[mario.walter () bluewin ch]

Hi List

we are going to setup a WLAN in a warehouse to enable the forklifters to
communicate with with the warehouse management (WM) system. The company,
which will install all the equipment suggested to setup a Cisco Secure ACS
for security reasons. However, I would prefer the installation of a firewall
and having a separate network segment for this WLAN, because the traffic
between the WM system and the forklifts isn't critical at all, but the traffic
on the company LAN is. So, my idea is to restrict the traffic going through
this firewall to only the needed protocols and IPs (outgoing and incoming),
to protect the rest of the companys LAN.
Any thoughts, caveats, comments?

TIA

Mario