| 摘要 |
PURPOSE:To replace a digital substrate in on-line mode as it is without disordering the operation of a plant by holding the output state of the digital substrate and replacing the digital substrate without disconnecting wiring to a load. CONSTITUTION:Terminal plates 5 are provided corresponding to plural digital output substrate 1, and an on-off switch 6 and an operation pilot lamp 7 are arranged on each terminal plate 5. When the substrate 1 is replaced while its output transistor (TR) 11 is on, a switch 6 connected in parallel to the output circuit of the output TR11 of the terminal plate corresponding to the substrate 1 is turned on and the connector 8 connecting the terminal plate 5 to the substrate 1 electrically is pulled out to replace the substrate 1 thereafter. Consequently, the substrate 1 is replaced while its output state is held, and a held output is supplied from a terminal part 9 to an output relay 3 during the replacement period to turn on the pilot lamp 7, annunciating that. |
