Control electronics in each rack communicate with and provide power to the control electronics of each corresponding box, and control electronics in each freezer communicate with and provide power to the control electronics of each corresponding rack, and a host computer communicates with {TAIL ~ the control electronics} in {HEAD ~ each freezer} 
Control electronics in each rack communicate with and provide power to the control electronics of each corresponding box , and control electronics in each freezer communicate with and provide power to the control electronics of each corresponding rack , and a host computer communicates with { TAIL ~ the control electronics } in { HEAD ~ each freezer }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD