BENTLYNEVADA330130-040-01-00PLC的输出电路形式一般分为：继电器输出，晶体管输出和晶闸管输出三种。弄清这三种输出形式的区别，对于PLC的硬件设计工作非常有必要。下面以三菱PLC为例，简要介绍一下这三种输出电路形式的区别和注意事项，其它公司的PLC输出电路形式也大同小异。1、继电器输出电路(MR)优势：继电器输出可通过交流和直流，一般负载AC250V/50V以下，负载电流可达2A，因此，PLC的输出一般不宜直接驱动大电流负载（一般通过一个小负载来驱动大负载，如PLC的输出可以接一个电流比较小的中间继电器，再由中间继电器触点驱动大负载，如接触器线圈等）。劣势：继电器触点的使用寿命也有限制（一般数十万次左右，根据负载而定，如连接***负载时的寿命要小于阻性负载）。此外，继电器输出的响应时间也比较慢（10ms）左右，因此，在要求快速响应的场合不适合使用此种类型的电路输出形式。2、晶体管输出电路(MT)优势：晶体管相应速度快，适用于要求快速响应的场合，如高速输出发脉冲；由于晶体管是无机械触点，因此比继电器输出电路形式的寿命长。劣势：晶体管输出型电路的外接电源只能是直流电源，另外，晶体管输出驱动能力要小于继电器输出，允许负载电压一般为DC5V～30V，允许负载电流为0.2A～0.5A。这两点的使用晶体管输出电路形式时要注意。当然在常见输出中不止这些，常见的可控硅放大版等也需要做一些了解，只是其应用逐渐淘汰。3、NPN和PNP在实际工作理论中，我们需要记住几点一般PLC采用NPN接法，其公共端为0V，常见于三菱PLC中；反之PNP接法，公共端接高电平，常见于西门子PLC。4、当然不仅局限于PLC输入输出端信号，传感器也有不同接法PNP与NPN型传感器一般有三条引出线，即电源线VCC、GND，OUT信号输出线1、NPN类NPN是指当有信号触发时，信号输出线OUT和GND连接，相当于OUT输出低电平。2、PNP类PNP是指当有信号触发时，信号输出线OUT和VCC连接，相当于OUT输出高电平的电源线。CUTLER-HAMMERHFD3030LCIRCUITBREAKER*NEWINBOX*ASHCROFTBIMETALTHERMOMETER7JA-63461-009*NEW*LOTOF3NBSLIDEUNITTWA-16*NEW*ALLENBRADLEY1336S-BRF30-AN-?EN4-L4ESERIESD*NEWOUT...LOTOF20AMP1-502632-000RECPET***EBULKHEADFIBEROP...LOTOF5MICROSWITCHBZ-2R-A2*NEW*BRADCONNECTIVITY1200652084*NEWINBAG*LOTOF10LEGRIS31061262UNIONTUBE1/2"*NEWINAF...OPCON8170A-6501*NICE*CHAR-LYNN60036SEALKIT*NEWINAFACTORYBAG*PULSSL10.300*USED*Ort:VereinigteStaatenvonAmerikaSIEMENSQ1515NCCIRCUITBREAKER*USED*EMERSONMSC-075CABLE*NEWINABOX*ADVANCEDILLUMINATIONRL4260*NEWINABOX*MONROEELECTRONICS177*NEWNOBOX*PAPSTECA7010/9337010?10-3506*USED*INDUKTIVSCHALTE?RLA12.1037.25*NEWINBAG*LOTOF2HONEYWELL922AA1Y-A4P-L*NEWINFACTORYBAG*KEYENCELK-C5*NEWINBOX*ALLENBRADLEY1771-OBDSERIESC*NEWINBOX*FESTOGRXA-HG-1/8-QS-?6*NEWOUTOFABOX*PHOENIXCONTACTFLKM-D50-SUB/S*USED*LAMBDASWITCHINGPOWERSUPPLYJWT75-522/A*NEW*HONEYWELLBZH1-2RNLIMITSWITCH(WHITEBOX)*NEWINBOX...LOTOF100M20AP-270*NEWINBAG*CUTLER-HAMMERD20WMS2D20*USED*FUJIELECTRICEA53BUL5A*NEWINABOX*ROSEMOUNTANALYTICALXMT-T-HT-11*NEWINABOX*ENIDINEFP203373SHOCKABSORBER*USED*ALLENBRADLEY60-1600BSERIESB*NEWINABOX*FUJIELECTRICEA53BUL5A*NEWINABOX*ROSEMOUNTANALYTICALXMT-T-HT-11*NEWINABOX*ENIDINEFP203373SHOCKABSORBER*USED*ALLENBRADLEY60-1600BSERIESB*NEWINABOX*HITACHIJ300-110HFU*USED*PARTLOWZ217000*NEW*N6402PRECISIONLIMITSWITCH10316H89A*NEWINBOX*BMIGS-2POWERLINEMONITOR*NICE*HEIDENHAINPGM24600202*USED*PAPST5656S*USED*LOTOF50EMMEF1TERMINALBLOCKS*NEWINABOX*ATLASCOPCO.1089057449*NEWINFACTORYBAG*ABBSACEKT3VD-M*NEWINBOX*ENDRESS+HAUSERMONORACKII919517-0408*NEW*MICROSWITCH914CE20-6*USED*MICROSWITCH914CE20-6*USED*OMRONE3F-DS10Z1*USED*SPRECHER+SCHUHCT3-32*USED*PHOENIXCONTACT22-REL/KSR-24/2?1*USED*DAYTONTIMEDELAYRELAY5X829N*USED*SIEMENS3RH1122-2BB40*USED*NORGRENF74G-4AN-QP1*USED*SQUARED8501-L0-60120V*USED*FESTOAEVC-20-10-I-P*USED*MICROSWITCH1LS53*USED*ALLENBRADLEY190-P024SERIESA*USED*MAC712C-12-PI-111-?CA*USED*SOLON6PSW/HCP1*USED*MOELLERAT0-11-1-I*USED*ALLENBRADLEY42GTF-9002-QDSERIESA*USED*INTERMATICK4135*USED*HONEYWELL914CE2-9*USED*MICROSWITCHBZV6-2RN4LIMITSWITCH*USED*ALLENBRADLEY42GRP-9000-QDSERIESA*USED*MAXITROLR400*USED*OMEGALVF-115*USED*DECCOCOIL9-174M115/60V*USED*R-KELECTRONICSTUB-115V-2*USED*AUTOMATIONDIRECTC18P-AN-2E*USED*TURCKKBE3T-1.5-SBE3T*USED*ALLENBRADLEY700-HT12AZ12SERIESA*USED*AUTOMATIONDIRECTVK1-A0-1B*USED*TELEMECANIQUEXS1M18FA260*USED*SCHMERSALSRB-NA-R-C.17-2?4VSAFETYRELAYMODULE*USED*PEPPERL+FUCHSMPH-D2AQ*NEWINABOX*DELTROL10000-40FLOWCONTROLVALVE*USED*ALLENBRADLEYANALOGCOMBINATIONMODULE1746-NIO4ISERI...LOTOF5LEVITON6599/712GROUNDFAULTCIRCUITINTERRUP...LOTOF2PHOENIXCONTACTE221474CABLE*USED*BINDICATORRB-HSENSOR*NEWINABOX*LOTOF5CLEVISPINS11-29T3/4X3*NEWINAFACTORYBAG...OMRONPROXIMITYSENSORAMPLIFIER(DC)E2CA-AL4C*USED*ITTMS3470L14-4S*NEWOUTOFABOX*TDKRAX5-10K*USED*TELEMECANIQUEPLUG-INRELAYRUN31A21BD*USED*LOTOF2ALLENBRADLEY1771-OASERIESB*USED*MACVALVE45A-AA2-DAAA-1C?M*NICE*AUTOMATICTIMING&CONTROLS6501-270-05-00*USED*EXIDELIGHTINGLIGHTGUARDM126*USED*B&R3BM150.9*USED*TRI-TRONICSF-A-36T*USED*NUTECHMAR-2*USED*FORMAX802351*USED*RALCOMANUFACTURINGCO.PRG-322(ASPICTURED)*USED*HONEYWELLRP818A10041*USED*ALLENAIRA-BC1-1/8X1*USED*ACTIONPAK9046-101*USED*WESTINGHOUSE503***85G.02*USED*SCHROEDERINDUSTRIESA-LF2919DC-30*USED*HONEYWELLT12-D418*USED*MTECOMPONENTSL100WSSER.D*USED*I***T18-A210*USED*I***T12-A118-F*USED*TOYO95-02*USED*ALLENBRADLEY193-EEBBSERIESB*USED*PARKERT20025D2F01*USED*SPEEDAIRE4Z027A*USED*MUFFINMU3B1*USED*HYDACVM5/210-C*USED*ROYALFANUT676DX-TP*USED*I***1280-1-A*USED*REGENTCONTROLINC.TM222*USED*LOTOF7RELECOS3-B*USED*TORK2002PHOTOCONTROL*USED*INDUSTRIALCONTRTROLINTERFACEBOARDOC-13-531-3564ANORGREN11-002-037*USED*REES00294-001*USED*ABSOLUTEPROCESSINSTRUMENTSAPI1200*USED*FAIRCHILDMODEL10ED1825*USED*DURANT6-Y-1-RMF-PMU*USED*HYDROSORB260A-HS-30*USED*LOTOF5LEGRAND00-63A*USED*DWYER3006C*USED*DWYER190035-10VALVE*USED*NORGRENMH01CDA32B001*USED*ACRISON115-1050*USED*POWERLIGHTINGE332PI120G01*USED*RUSSELLSTOLL3F0404*USED*CISCOSYSTEMS37-0723-010508*USED*SQUAREDCIRCUITBREAKERKA36125*NEWINBOX*AIRPAX0-6RPMX1000TACHOMETER*NEWINABOX*BOSHMP06703589*USED*MILLTRONICSAO-10*USED*JAMESBURYACTUATORVPVL350SR4/5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