MULTI-POINT INPUTTING TWO-WIRE TRANSMITTER

PURPOSE:To attain multi-point measurement for temperature or the like by eliminating the necessity of a power supply of large capacity for a master device and connecting only one two-wire transmission line between the master device and this multi-point inputting two-wire transmitter. CONSTITUTION:The transmitter is provided with a main power supply generating circuit 7 and local power supply generating circuits 8-1 to 8-4. The circuits 7, 8-1 to 8-4 receive current supply from the transmission line L1 and respectively generate main power supply PWRM and local power supplys PWR1 to PWR4. The main power supply PWRM is always supplied to a main CPU 4'. The local power supplies PWR1 to PWR4 are successively supplied to A/D conversion circuits 1-1 to 1-4, sub-CPUs 2-1 to 2-4 and isolation circuits 3-1 to 3-4.