厦门航拓电气有限公司现货销售 0592-5072116 Q Q：565167042 由于PLC以微处理器为核心，故具有微机的许多特点，但它的工作方式却与微机有很大不同。微机一般采用等待命令的工作方式，如常见的键盘扫描方式或I/O扫描方，若有键按下或有I/O变化，则转入相应的子程序，若无则继续扫描等待。 PLC则是采用循环扫描的工作方式。对每个程序，CPU从第一条指令开始执行，按指令步序号做周期性的程序循环扫描，如果无跳转指令，则从第一条指令开始逐条执行用户程序，直至遇到结束符后又返回第一条指令，如此周而复始不断循环，每一个循环称为一个扫描周期。扫描周期的长短主要取决于以下几个因素：一是CPU执行指令的速度；二是执行每条指令占用的时间；三是程序中指令条数的多少。一个扫描周期主要可分为3个阶段。 1．输入刷新阶段 在输入刷新阶段，CPU扫描全部输入端口，读取其状态并写入输入状态寄存器。完成输入端刷新工作后，将关闭输入端口，转入程序执行阶段。在程序执行期间即使输入端状态发生变化，输入状态寄存器的内容也不会改变，而这些变化必须等到下一工作周期的输入刷新阶段才能被读入。 2．程序执行阶段 在程序执行阶段，根据用户输入的控制程序，从第一条开始逐步执行，并将相应的逻辑运算结果存入对应的内部辅助寄存器和输出状态寄存器。当最后一条控制程序执行完毕后，即转入输入（出？）刷新阶段。 3．输出刷新阶段 当所有指令执行完毕后，将输出状态寄存器中的内容，依次送到输出锁存电路（输出映像寄存器），并通过一定输出方式输出，驱动外部相应执行元件工作，这才形成PLC的实际输出。
440RP23071Guardmaster MSR22LM Safety Relay 440R-P23073440RP23073Guardmaster MSR23M Safety Relay 440R-P4NANS440RP4NANSGuardmaster MSR45E Extension Module 440R-S07139440RS07139Guardmaster CU2 Safety Relay 440R-S07140440RS07140Guardmaster CU2 Control Unit Relay 440R-S07279440RS07279Guardmaster CU2 Control Unit Relay 440R-S07280440RS07280Guardmaster CU2 Control Unit Relay 440R-S07281440RS07281Guardmaster CU2 Control Unit Relay 440R-S07283440RS07283Guardmaster CU2 Control Unit Relay 440R-S07284440RS07284Guardmaster CU2 Control Unit Relay 440R-S12R2440RS12R2Guardmaster Single Input Safety Relay 440R-S13R2440RS13R2Guardmaster Single Input Safety Relay 440R-S23173440RS23173Guardmaster CU4 Safety Relay 440R-S23174440RS23174Guardmaster CU4 Safety Relay 440R-S23175440RS23175Guardmaster CU4 Safety Relay 440R-S35001440RS35001Guardmaster CU3 Safety Relay 440R-S35002440RS35002Guardmaster CU3 Safety Relay 440R-S35003440RS35003Guardmaster CU3 Safety Relay 440R-S845AER-NNL440RS845AERNNLMSR57P Speed Monitoring Safety Relay 440R-T07114440RT07114Guardmaster CU1 Safety Relay 440R-W23217440RW23217Guardmaster MSR329P Safety Relay 440R-W23218440RW23218Guardmaster MSR320P Safety Relay 440R-W23219440RW23219Guardmaster MSR310P Safety Relay 440R-W23220440RW23220Guardmaster MSR312P Safety Relay 440R-W23221440RW23221Guardmaster MSR330P Group1 Safety Relay 440R-W23222440RW23222Guardmaster MSR330P Group 2 Safety Relay 440R-W23223440RW23223Guardmaster MSR330P Group3 Safety Relay 440R-W23224440RW23224MSR338P Time Delay Expansion Module 440R-W23225440RW23225MSR338P Time Delay Expansion Module 440R-W23226440RW23226MSR338P Time Delay Expansion Module 440R-ZBE820AZ1440RZBE820AZ1Guardmaster MSR19E Safety Relay 440R-ZBE820AZ2440RZBE820AZ2Guardmaster MSR19E Safety Relay 440R-ZBL220Z24440RZBL220Z24Guardmaster MSR17T Safety Relay 440R-ZBR520AZ1440RZBR520AZ1Guardmaster MSR18T Safety Relay 440R-ZBR520AZ2440RZBR520AZ2Guardmaster MSR18T Safety Relay 440S-M470300440SM470300SIGMA NON CONTACT SWITCHES 440S-M470303440SM470303SIGMA NON CONTACT SWITCHES 440S-M471161440SM471161SIGMA NON CONTACT SWITCHES 440S-M545002440SM545002SIGMA NON CONTACT SWITCHES 440S-M545005440SM545005SIGMA NON CONTACT SWITCHES 440S-M545008440SM545008SIGMA NON CONTACT SWITCHES 440S-M545009440SM545009SIGMA NON CONTACT SWITCHES 440S-M545013440SM545013SIGMA NON CONTACT SWITCHES 440S-M545038440SM545038SIGMA NON CONTACT SWITCHES 440S-M545039440SM545039SIGMA NON CONTACT SWITCHES 440S-M545040440SM545040SIGMA NON CONTACT SWITCHES 440S-M545098440SM545098SIGMA NON CONTACT SWITCHES 440S-M565052440SM565052SIGMA NON CONTACT SWITCHES
1C31166G01 1C31166G01 1C31179G02 1C31179G02 1C31181G02 1C31181G02 1C31189G01 1C31189G01 1C31192G01 1C31192G01 1C31197G01 1C31197G05 1C31197G01 1C31219G01 1C31219G01 1C31224G01 1C31224G01 1C31224G01 1C31224G01 1C31238H01 1C31238H01 1P00028G01 1P00028G01 1TGE120010R1000 200-CICN 2094-AC09-M02 2094-AC09-M02 2094-AM02-S 2094AM02-S 2094-BMP5-S 2094-BMP5-S 2098-DSD-010X 2098-DSD-010X 2098-DSD-010X-DN 2098-DSD-010X-DN 2150-AGA 1747-KE 269PLUS-100P-120 2706-M1N1 2711-B5A10 2711-B5A10 2711P-T10C4D2 2711-T10C8X 2711-T10C8X 2711-T9C1X 2711-T9C1X 3300/03 3300/03-01-00 3300/16 3300/16-15-01-03-00-00-00 3300/20 3300/20-13-03-01-00-00 3300/20 3300/20-12-02-00-00-00 3300/20-05-03-01-00-00 3300/46 3300/46-46-04-02-01 3300/47 3300/47-XX-XX-01-00 3300/65 3300/65-14-01-00-00-01-00 330100-50-00，带包装330100-50-00。价格超好 330101-00-16-10-02-00 330101-00-30-10-02-00 330101-00-50-10-02-00 330103-00-04-10-02-CN 330103-00-05-05-02-00 330103-00-05-10-02-00 330103-00-06-10-02-00 330103-00-10-10-02-00 330103-00-14-10-01-00 330104-00-06-10-11-00 330104-00-11-10-02-05 330104-00-12-10-02-00 330105-02-12-10-02-00 330105-02-12-20-02-05 330106-05-30-05-02-05 330106-05-30-10-02-00 330106-05-30-10-02-CN 330130-045-00-05 330130-080-00-00 330130-085-00-00 330180-50-00 330180-50-05 330180-51-05 330180-90-00 330180-90-05 330180-91-00 330780-91-00 330709-000-070-10-02-00 330730-040-00-00 330780-50-00 330780-51-00 330780-90-00330780-90-00 330850-50-05 330851-04-000-023-10-01-05 330910-05-10-02-00 330930-065-02-00 330980-50-00 330980-50-00 440S-M565055440SM565055S
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