the second device is driven by the second power supply, and capable of performing {HEAD ~ a communication} via {TAIL ~ the bus} in the condition in which the pull up voltage is equal to the second predetermined voltage, wherein 
via
the second device is driven by the second power supply , and capable of performing { HEAD ~ a communication } via { TAIL ~ the bus } in the condition in which the pull up voltage is equal to the second predetermined voltage , wherein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH