.SELOGYT223001-ACYXT121A.SELOGYT223001-ACYXT121A.SELOGYT223001-ACYXT121A专业提供：PLC可编程控制系统，分散控制系统（DCS）安全仪表系统（SIS），ESD系统，振动监测系统，汽轮机控制压缩机组控制系统（CCS）等各类工控系统部件系统里的PLC模块，DCS模块，CPU模块，IO模块，DO模块，AI模块，DI模块，网络通信模块，以太网模块，运动控制模块，模拟量输入模块，模拟量输出模块，数字输入模块，数字输出模块，冗余模块，电源模块，继电器输出模块，继电器输入模块，处理器模块因为想到电脑与PLC的连接电缆（第1种常规的连接电缆）为2-2短接、3-3短接、5-5短接，所以考虑直接用USB←→RS232电缆将电脑和PLC连接起来，如果这样可以的话不就省了一条连接电缆了吗？下面是直接用USB←→RS232电缆将电脑和PLC连接起来的试验结果：有时间第1次通信时出现以下错误：“所选的端口被另一个应用所占用”；第2次通信时出现以下错误：为什么电脑通过上述两种连接电缆与PLC连接没有问题，而直接采用USB转RS232电缆线与PLC连接却不行呢？以下是分析过程：第1种可能：阻抗的原因。虽然上述两种连接电缆为直连线，却有阻抗存在，多了这个阻抗就可以正常连接。但这个原因好像很牵强，连笔者自己都不能相信。第2种可能：该USB转RS232的公头与PLC的母头接触不良，而加一根电缆却能连接正常——USB转RS232的公头与连接线的母头接触良好，连接线的公头与PLC的母头接触良好。该猜测来源于笔者遇到过的一次电脑故障：某台电脑的鼠标无法使用，另外换一个鼠标正常，把故障鼠标换到其它电脑却能正常使用。最后怀疑鼠标接头与主板插口接触不良，就将鼠标插头破开再涂上一层焊锡，结果使用正常！但是对于USB转RS232的公头与PLC的母头接触不良这种猜测，笔者觉得可能性不大——因为他解释不了“所选的端口被另一个应用所占用”这个故障。最后想到了另外一个可能：USB转RS232直接与PLC连接就相当于USB转RS232的串口与PLC的串口1-1、2-2、3-3、4-4、5-5、6-6、7-7、8-8、9-9一一对应连接，而通过连接线却只有2-2、3-3、5-5三对端子连接，这说明1-1、4-4、7-7、8-8、9-9至少有一对是不能连接的，否则就会出现问题，而且这还既有可能损坏PLC与电脑的通信端口。1756M1351195156-30051400700-10051401286-100J-DIM00J-MHM10J-MSC10PCD4.B90DS200CDBAG1B140XTS00200140ACI03000MA-0185-100MA-0186-1001746-NI8IC693MDL231DC24VPCI-6115140XTS00200140DAO85300IC670MDL241XFR600-4CIMR-08AX3-10021746-NI8A5E012317223HAC16831-11756-PB726GK1543-0AA02CT3-3232A1746-NI04I1756-IM16I1769-PA41769-SDNQPI31200S2P-B1784-PKTX140ARI03010FNT00501785-KE1336-L41756-L62A20B-2002-03105X00105G07SP-231N1746-IM161746-P41336-L5E1768-L431756-L62PTQ-PDPMV1IC670MDL331IC697MDL750140CPS11420140NOE771011785-L20B140ACI03000140ARI03010140CPS21400140CRA93200140CRP93200140DAI75300140DAO85300140XTS00200CM31BP30-ONSP38-6NDFP11A140CPU43412A140CHS11000140CPS11420140CRP93200140CPS21400140CPU113031747-L5521771-ASB1771-P71771-P4S1747-L553140CPS114200-51378-25PC-E984-685CORONA_27030_0103REV.BFRE-201A-1ZC98043-A1601-L140ARI03010140ATI030006DD1681-0CA26DS1412-8RR6DS1717-8RR6DS1723-8BBIPM-P0904HA1746-A101746-A71756-A101771-A4B2711-NM14SW925AE1756-OF8SST-PFB-SLC1746-IA16T1F-08AD-1NR-TH081746-NI16I1746-NO8IZW-102PM6ES7315-2AF03-0AB0MDV60A0110-5A3-4-00IC670ALG3101746-IM161746-OW161747-L532IC693CMM3211C31227G011B30035H011C31164G021C31224G01A03B-0808-C0201249AFBM09FBM41P0972AJPROVIT52003HNE00314-11C31194G011C31197G01140XBP01000140ACI03000PCI-61151746-N33HAB8101-146TF-5C1747-SDN3UF5011-3BB10-16ES7416-3XL04-0AB0IC693MDL645EIC693MDL940HEVR1161756-OX8I1756-A101756-A131756-A71756-CNB1756-CP31756-DNB1756-ENBT1756-IB16I1756-N21756-TBCH6ES7470-0AA00-0AA0UDX5107-G2-2UDX5114-G4-2M063-LE-507E1756-CNBR/E1756-IF161756-OF8140DAI74000140DAO84210MPL-A320H-HJ22AARCA-S-SA5RCA-S-SSIC693CMM3211747-ASB1747-L5421747-SN140DRA84000140ACI04000140ACO13000140CPS11420140CRA93200140DAI75300IC695PSD140B140CPU11302IS215UCVEM06AXFL521BIC693CMM321-JJDAVCDIGITALCONTROLLERETC902-NSCP-L850-400-G11606-XL240EIBRC-6032R1746-IA16HCMC03MC-OB26540168802140CPS11420140CPU65150140CRA93200140CRP93200140ACI03000IC697CMM7421756-ENBT140XBE10000140ARI03010140CPS21400140XTS00200140XBP00600140XCA71703140XCP510001756-L61PC-A984-1451203-CN1MVME162-212MVME162PA-252SE2711-T10C101746-IB161746-NO4V1746-NT41746-OB161746-P31746SC-NT81747-L5511747-SDN/BIC693BEM331IC693CPU364IC693PWR331KPS-60/20-ESCKSD1-08KSD1-32KSD1-48SST-PFB-SLC1746-OB16E1747-L542TSX3708001SST-PFB-SLCIC693MDL655140CRP93200140XBP01000CIMR-E7U47P51756-ENBT140ARI03010140ATI03000HE693THM166E30004380A140CRP93200140CPU43412A1C31224G01/1C31227G01PCI-6013IC697MDL350RFT9739D4140XBE10000SST-PFB-CLXMDX-052EVS9325-EP1203-CN11746-NO4VC628-810021746-NI8IC697CMM7421746-IB161746-N04V1746-NI41746-OW166DR1900-56DR2100-5HE693PBM101ELS6804-I400A1756-OF41785-V40LECPNC3-0PNC3ECCP60-01140DAI55300140CPS21400505-4332505-6108B505-6660545-1105IPM2-P0904HAP0903ZEP0971WV-DNBTIC697CMM742SDCS-CON-1XBTP0210101756-PA75RMK9906N.821756-M221747-L542DSQC6393HAC025097-001/08运费140DD035300AD202HGP0912ZVP0914XBP0914YM(FCM10E)P0914ZXP0916NAP0926JMAP0973CA(FEM100)SMARTSWITCH2200/2H258-17REWS600-241756-L61A-404LP3HAC16831-11746-NI46SE6411-6BD22-2CA1C500-PS222EJAMSC-B2743V6SE3214-0DA401756-EWEB35AE92GJR5137200R0002140CPS21400UDX51285X00105G071746-OB16E140ACI04000140CPS21400140CPU65150140DDI35300140DDO35300140DDO84300140NOE77101140XBP01000140XTS00200140ACI03000140ERT85410ZMVME162-020AMVME224A-3FCP2701746-P4140AVO020001336F-BRF75-AE-EN5.5KW1756-BA2AGDR-71C1756-ENBTXDM100140CPS21400140CPU65150140DDO35300140NOE77101140XBP01000140XTS00200140ACI04000140DDI35300140ERT85410Z140XCP51000140CPS11420140NOE77101140XBP010001746-NI81756-BA11756-PA721794-OW8IC693MDL646ECPP60-01EM1410AF4-05220316IN/161756-DNB1770-KFD140ACI030001794-IF4I140DDO35300140NOE77101140CPS21400140DDO35300490NAE911001756-CNBR/E1756-ENBT/A140DDI3531051195156-30051400700-10051401286-100J-DIM00J-MHM10J-MSC101746-NO4VC500PS222E2711-K6C10PS-M06D12S5-NJ1L(S)1C31113G021C31129G031C31161G0237063708E9566-8109765-6109766-2103504EM063-LE-507E1756-DNB1746-OB161746-OB8MVME13364-W5001B01C1785-L20B467NHP8110000-113-406FAIN-XVME-566TC-PRS0211756-CNBR/E1756-ENBT/ACM31140ACI03000PT40-H404-2-02C140ACI03000140NOE77100E2E-X1C1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