| 摘要 |
PURPOSE:To identify a slave station executing an abnormal transmission by adding an FF holding a history of transmission operation to a slave station and displaying it. CONSTITUTION:When the slave station 7 transmits a signal, a communication control terminal TXGATE is set to logical ''1'', and after a communication driver 3 is opened, a signal is outputted to a transmission line 1 from a transmission terminal TXD. When the transmission is finished, the level of the terminal TXGATE is brought into logical ''0'' and the driver 3 is closed and then the output to the transmission line 1 is finished. When the communication is executed even once, the transmission hold FF4 is set and the transmission holding LED5 continues lighting. Thus, even if a condition not executing transmission logically is set and the transmission hold LED5 is lighted, an abnormality of the slave station is detected. |
