各种PLC的输入接口电路结构大都相同,按其接口接受的外信号电源划分有两种类型:直流输入接口电路、交流输入接口电路。其作用是把现场的开关量信号变成PLC内部处理的标准信号。PLC的输入接口电路如图2所示。 在输入接口电路中,每一个输入端子可接收一个来自用户设备的离散信号,即外部输入器件可以是无源触点,如按钮、开关、形程开关等,也可以是有源器件,如各类传感器、接近开关、光电开关等。在PLC内部电源容量允许条件下,有源输入器件可以采用PLC输出电源(24V),否则必须外设电源。 1747-M3 EEPROM MEMORY,4K 1747-M4 EEPROM MEMORY,4K 1747-M5 ADAPTER SOCKET-PKG. 5 1747-NP1 WALL MOUNT PWR SUPPLY 120V AC INPUT 1747-NP2 GLOBAL DESK TOP PWR SUPPLY 85/285 V AC IN 1747-OCAPINT WINDOWS NT API FOR 1771-OC MODULE 1747-OCDPDE OC DOC SET/GERMAN 1747-OCDPES OC DOC SET/SPANISH 1747-OCDPFR OC DOC SET/FRENCH 1747-OCDPIT OC DOC SET/ITATIAN 1747-OCDR16 16 MB DRAM FOR 1747 OPEN CONTROLLER 1747-OCDR32 32 MB DRAM FOR 1747 OPEN CONTROLLER 1747-OCDR4 4 MB DRAM TO 1747 OPEN CONTROLLER 1747-OCENET ETHERNET(10/100 BASET)MODULE 1747-OCF 266 MHZ OPEN CONTROL PROCESSOR 1747-OCFAN1 FAN ASSEMBLY FOR 1747 OPEN CONTROLLER 1747-OCIDE1 ATA CARRIER CARD/IDE DRIVE EXPANDER MODULE 1747-OCIDE25 2.5 IDE DRIVE EXPANSION MODULE 1747-OCKTX SINGLE CHANNEL 1-B COMM OPTION MODULE 1747-OCKTXD DUAL CHANNEL A-B COMM OPTION MODULE 1747-OCP252 PARALLEL ADAPTER CABLE 1747-OCPCI2 2-SLOT PCI BUS FOR 1747 OPEN CONTROLLER 1747-OCPCI3 3-SLOT PCI BUS FOR 1747 OPEN CONTROLLER 1747-OCPCI4 4-SLOT PCI BUS FOR 1747 OPEN CONTROLLER 1747-OCPCI5 5-SLOT PCI BUS FOR 1747 OPEN CONTROLLER 1747-OCPCI6 6-SLOT PCI BUS FOR 1747 OPEN CONTROLLER 1747-OCPCM1 PCMCIA OPTION MODULE 1747-OCPCM2 PCMCIA OPTION MODULE WITH CARD & SOCKET 1747-OCS92 SERIAL ADAPTER CABLE 1747-OCSBC SERIAL BOOT CABLE 1747-OCSDCK FLASHDRIVE CABLE KIT FOR 1747 OPEN CONTROLLER 1747-OCTS OPEN CONTROLLER FAMILY SUPPORT CONTRACT 1747-OCUS OPEN CONTROLLER FAMILY UPDATE SERVICE 1747-OCVGA1 VGA OPTION MODULE FOR 1747 OPEN CONTROLLER PCI BUS 1747-OCVGAE COMBO OPTION MODULE 1747-PCIAA 1747 PCI BUS INTERFACE KIT 1747-PCIAB 1747 PCI BUS INTERFACE KIT 1747-PCIBA 1747 PCI BUS INTERFACE KIT 1747-PCIBB 1747 PCI BUS INTERFACE KIT