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