| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide optical field bus equipment capable of eliminating the need of replacement of a battery without impairing the characteristics thereof and an optical field bus system using the optical field bus equipment. SOLUTION: This optical field bus equipment is connected to optical fibers 3A and 5A as transmission media to exchange optical signals so as to communicate with a host control device 11. The equipment comprises a power circuit 25 receiving a power supply from an external power supply line 61, a secondary battery 20, a battery charging circuit 28 for charging the secondary battery 20 from the power circuit 25, a low voltage detection means 27 for detecting a voltage drop of the power circuit 25, and a power switching circuit 29 for switching the power supply to the internal circuit of the optical field bus equipment 2 from the power supply from the external power supply line 61 to the power supply from a secondary battery circuit system. Normally, the device is operated on the power supply from the external power supply line 61 and, when the voltage drop detection means 27 detects the voltage drop of the power circuit 25, operated on the power supply from the secondary battery 20.</p> |
