Advice on setup for multiple subnets to communicate with one master UPS on its own subnet.

We currently have one cabinet of servers running off an Eaton UPS via RS232 to the main server, each subsequent server in the rack receives its power source from the master computer. In the event of a power outage the UPS triggers the Main server, which then cascades down to all our secondary servers. This works fine, everything is on the same IP range 192.168.1.x.

I've been tasked with adding two more cabinets, and two more master servers in each rack with a few secondary servers, lets call those racks 192.168.2.x and 192.168.3.x. Each cabinet will have its own switch, and we do not want traffic or computers visible from one subnet to another. We do want the UPS to control all systems for shutdown and power, so I'm leaning towards pulling it off the main 192.168.1.x system, tossing in an NMC and putting it on its own IP range, something like 192.168.100.1.

I think the best solution is to setup a master switch (We have Dell S4128F switches for all of this running 10gb fiber) to have the UPS on Port 1, rack 1/2/3 on ports 2/3/4 and setup a VLAN so that each rack can talk to the UPS port, and the UPS can talk back, but keep traffic private so that each rack can't see each others ports.

Does that sound right? I saw that APC's NMC offer unicast support so you don't have to do anything like that, but it looks like Eaton does not. Any advice would be appreciated as I've been out of the game for awhile.