JPH01146739U

JPH01146739U -

Info

Publication number: JPH01146739U
Application number: JP1988035294U
Authority: JP
Priority date: 1988-03-18
Filing date: 1988-03-18
Publication date: 1989-10-11

Description

[Brief explanation of the drawing]

第１図は本考案の実施例を示す回路図、第２図
及び第３図は従来技術を示す回路図である。図面中、１はフエイルセーフリレー、２は電源
、１０は負荷駆動回路、１２は判定回路、２０は
負荷、３１は駆動指令部、４０はモニタ部、ｌ１
は供給ライン、ｌ４０はモニタライン、ｌ５０は
接続ライン、Ｒ１はプルダウン抵抗、Ｒ４０はプ
ルアツプ抵抗である。 FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are circuit diagrams showing the prior art. In the drawing, 1 is a fail-safe relay, 2 is a power supply, 10 is a load drive circuit, 12 is a judgment circuit, 20 is a load, 31 is a drive command section, 40 is a monitor section, l1
is a supply line, l40 is a monitor line, l50 is a connection line, R1 is a pull-down resistor, and R40 is a pull-up resistor.

Claims

[Claims for Utility Model Registration] A fail-safe relay that is closed when the system is normal and passes current sent from a power source, and that opens when the system is abnormal and cuts off the current; A switching element is connected between the load and performs a switching operation according to the state of the drive command signal, and when current flows from the switching element to the load, the judgment terminal is grounded and current flows from the switching element to the load. A load drive circuit includes a determination circuit that sets the determination terminal to a high impedance state if the determination terminal is not present, a monitor unit connected to the determination terminal via a monitor line, and a pull-up resistor connected to the monitor line to pull up the monitor line. and a pull-down resistor that is connected to this supply line and whose resistance value is smaller than the resistance value of the pull-up resistor in order to pull down the supply line connecting the fail-safe relay and the switching element, and further connects the monitor line and the supply line. A signal monitor circuit comprising: a connection line interposed with a diode that prevents current from flowing from the supply line side to the monitor line side;