1）PLC系统设计时，要充分利用PLC内部错误及故障自检测功能，如FX系列的M8004错误检测、M8005电池电压低检测和M8000正常运行监视等，它们能有效检测及监视PLC的运行状态。只要适当的运用及输出指示，就能方便操作工及维

护人员快速辨明是PLC内部故障还是外部故障。

　　2）大量的工程实践证明，PLC系统外部元件故障率远要高于PLC本体故障率。因此，为了提高整个系统的可靠性，PLC外部的输入、输出元件的故障检测，除了在硬件上采取措施外，还必须在软件中加强故障检测程序。常用的设计方法有两种：（1）时间故障检测法，如图5a所示：Y001输出时同时启动一个内部时间继电器T1，2s后KM无反馈信号，则认为KM故障或控制回路故障，经M1启动报警及指示程序。（2）逻辑错误检测法，如图5b所示：X001、X002、X003为逻辑“与真”条件，当有一个条件不成立时，Y001停止输出，自认为系统有故障，停止正常的工作程序，并启动报警及指示程序。

图5 外部元件故障检测方法

　　3）作为系统报警提示的“声/光”报警，两者存在缺一不可。例如我公司水泥粉磨系统中的报警信号的选择与设计都较为理想，唯独是“声/光”报警之中的“光”提示欠缺。现场磨机噪声极大，操作工稍不留神，根本无法听到音响报警，对操作工来说，这是极大的不便。

　　最后，PLC控制系统作为一个系统工程，设计者在设计时，必须要有一个系统的认识和了解，渗透整个系统的工艺流程及控制要求，做到满足客户、方便客户，力求系统的完善。

Horiba STEC SEC-A21DM Mass Flow Controller AMAT 3030-00782 New

Horiba STEC SEC-A21DM Mass Flow Controller AMAT 3030-00778 New

Horiba STEC SEC-A21DM Mass Flow Controller AMAT 3030-00770 New

Horiba STEC SEC-A21DM Mass Flow Controller AMAT 3030-00804 New

Millipore FC-2900MEP5 Mass Flow Controller AMAT 0227-45305 New

STEC LF-F404M-A-EVD Liquid Mass Flow Meter ATRP 2g/min AMAT 0190-38185 New

STEC LF-F404M-A-EVD Liquid Mass Flow Meter TEOS 5g/min AMAT 0190-38187

STEC SEC-4600M Mass Flow Controller AMAT 3030-09676 100 SLM N2 New

Unit Instruments UFC-1100A Mass Flow Controller AMAT 3030-01058W New Surplus

Mykrolis FC-2900MEP Mass Flow Controller AMAT 3030-02224 New

Millipore FC-2900M Mass Flow Controller AMAT 0226-44365 New

Tylan FC-2900MEP Mass Flow Controller AMAT 0227-06244 New

Mykrolis FC-2900M Mass Flow Controller AMAT 0226-49258 New

Millipore FC-2950MEP5 Mass Flow Controller AMAT 0227-38164 New

Tylan FC-2900MEP Mass Flow Controller AMAT 0224-43258 New

Tylan FC-2902MEP-T Mass Flow Controller AMAT 0225-41918 New

Tylan FC-2900MEP Mass Flow Controller AMAT 0225-41260 New

Tylan FC-2900 Mass Flow Controller AMAT 3030-04986 New

Tylan FC-2900MEP5 Mass Flow Controller AMAT 0227-12489 New

Tylan FC-2950MEP5 Mass Flow Controller AMAT 0226-43226 New

Millipore FC-2900MEP5 Mass Flow Controller AMAT 0227-04127 New

Tylan FC-2900MEP-L Mass Flow Controller AMAT 0227-06163 New

Millipore FC-2902MEP-T Mass Flow Controller AMAT 3030-04046 New

Horiba STEC SEC-Z11DWM Mass Flow Controller AMAT 0190-12302 New

Mykrolis FC-2900MEP Mass Flow Controller AMAT 3030-02222 New

Mykrolis FC-2900MEP Mass Flow Controller AMAT 3030-02223 New

Unit Instruments UFC-1400A Mass Flow Controller AMAT 0225-10169 New

Tylan FC-2900MEP5 Mass Flow Controller AMAT 3030-08700 Lot of 3 As-Is

Tylan FC-2900MEP5 Mass Flow Controller AMAT 3030-09020 Lot of 3 As-Is

Mykrolis FC-2900MEP-4V Mass Flow Controller AMAT 3030-02224 New

Millipore FC-2900M Mass Flow Controller AMAT 0226-49259 New

Tylan FC-2900MEP-L Mass Flow Controller AMAT 0227-06162 New

Tylan FC-2902M-T Mass Flow Controller AMAT 3030-04023 New

SAM Hitachi MFC SFC2482FA H2 20 SLM DeviceNet Surface Mount New

SAM SFC2480FA Mass Flow Controller O2 5 slm MFC new

Sam Hitachi SFC2480FA He 5SLM MFC Mass Flow Controller new

SAM Hitachi MFC SFC1483FA N2 100 SLM DeviceNet Surface Mount New

Unit MFC UFC-1160A CF4 100 SCCM CardEdge 1/4 VCR New

STEC LF-F404M-A-EVD Liquid Mass Flow Meter Horiba AMAT 0190-38191 New

Aera FCPIDN980CBA Mass Flow Controller PI-980 New Surplus

Hitachi MFC SFC2483FA SurfaceMount DeviceNet N2 50SLM New

STEC Mass Flow Controller SEC-4500MC-SUC-?016 Flow Meter SEF-4500M Lot of 3

Millipore MFC FC-2951MEP5 0227-46754 1/4 VCR CardEdge N2 5 SLM New

Millipore MFC FC-2951MEP5 0227-06138 1/4 VCR CardEdge HBR 200 SCCM New

Millipore DSKRD100 Mass Flow Controller AMAT Applied Materials Lot of 3

Unit UFC-8165 Mass Flow Controller Digital UltraClean Metal Seal Lot of 3 As-Is

Horiba STEC LF-F40M-A-EVD Liquid Mass Flow Meter AMAT 3030-15270 Lot of 3 As-Is

Horiba STEC SEC-Z11DM O2 5SLM 0190-16813 MFC Mass Flow Controller New

Horiba STEC SEC-Z11DMC AR 100SCCM 3030-13072 MFC Mass Flow Controller New

Horiba STEC SEC-Z11DM AR 200SCCM 3030-13071 Surface Mount DeviceNet MFC New

Horiba STEC SEC-Z11DM He 300SCCM 3030-13079 Surface Mount DeviceNet MFC New

Millipore FSEGD100XJ00 C4F6*1 100SCCM Surface Mount DeviceNet MFC New

Millipore FSEGD100XN00 C4F6*1 200SCCM Surface Mount DeviceNet MFC New

Millipore FSCGD100BX00 CH3F 50SCCM Surface Mount DeviceNet MFC New

Mykrolis FC-2950MEP5 N2 20SCCM 3030-12825 1/4"VCR CardEdge MFC New

Aera FC-DN780C-BA NF3 100SCCM 0190-23476 Surface Mount DeviceNet MFC New

Aera FC-DN780CPBA Ar 200SCCM 3030-13113 Surface Mount DeviceNet MFC New

Celerity DSMAE1XM Mass Flow Controller AMAT 3030-15294 35-88 SCCM N2 New

Mykrolis FC-2900V N2(AR) 5 SCCM 3030-90052 CardEdge 1/4" VCR MFC New

Millipore FC-2950MEP5 O2 10SLPM 3030-09551 1/4" VCR CardEdge MFC New

Aera FC-PN880CBA AR 1000SCCM 3030-11805 Surface Mount DeviceNet MFC New

Millipore FSDGD100TV00 CH2F2 300SCCM Surface Mount DeviceNet MFC New

Millipore FSDGD100LG00 Mass Flow Controller AMAT 3030-03271 200 SCCM CH2F2 New

Millipore FSFAK500DA06 NH3 10000SCCM 1/4 VCR DeviceNet MFC New

Aera FC-PN980CBA SIF4 30 SCCM 3030-11807 Surface Mount DeviceNet MFC New

Aera FC-PN980CBA SIH4 300 SCCM 3030-11802 Surface Mount DeviceNet MFC New

Aera FC-PN980CBA SIF4 200 SCCM 3030-11803 Surface Mount DeviceNet MFC New

Aera FC-PN980CBA PH3 200 SCCM 3030-11804 Surface Mount DeviceNet MFC New

Aera FC-PN980CBA PH3 30 SCCM 3030-11808 Surface Mount DeviceNet MFC New

Aera TC FC-PN980CBAS Ar 100SCCM 0190-26708 MFC Mass Flow Controller new

Aera FC-DN780C-BA H2 1SLM 3030-14002 MFC Mass Flow Controller new

SAM SFC470F1MC-4VM SiH2Cl2 700 SCCM 1/4" VCR 15-Pin D-Sub MFC New

SAM SFC480F1W4 MC-4VM SiH4 100 SCCM 1/4" VCR 15-Pin D-Sub MFC New

Millipore FSBAK500WC06 SIH4 5SCCM 1/4" VCR DevicNet MFC New

Millipore FSDAK500DD06 SIH4 200 SCCM 1/4" VCR DevicNet MFC New

Horiba STEC LF-410A-EVD Liquid Mass Flow Meter TEOS Lot of 3 As-Is

STEC SEC-4400M Mass Flow Controller 60 SCCM WF6 Lot of 3 As-Is

STEC SEC-Z11DMC-SUC-?S5 Mass Flow Controller AMAT 3030-13071 Ar 200 SCCM New

STEC SEC-Z11DM Mass Flow Controller C4F6 300SCCM new

STEC SEC-7340M Mass Flow Controller 3030-11043 refurbished H2 3SLM

STEC SEC-V121DM Mass Flow Controller NH3 30SLM refurbished

STEC SEC-Z11DM Mass Flow Controller CH2F2 300SCCM new

STEC SEC-Z11DM Mass Flow Controller C4F8 300SCCM new

STEC SEC-Z11DM Mass Flow Controller C0 2SLM new

STEC SEC-Z11DM Mass Flow Controller CHF3 300SCCM new

STEC SEC-7330M Mass Flow Controller AMAT 3030-11042 New Surplus

STEC SEC-Z10DW He 5SLM MFC Mass Flow Controller SEC-Z11DWM new 0190-16810

STEC SEC-Z11DMC-SUC-?S5 Mass Flow Controller AMAT 3030-13079 He 300 SCCM New

Horiba STEC SEC-7355MO-RUC Mass Flow Controller AMAT 3030-03647 New

Celerity AATGD40W1 Mass Flow Controller IN3XP AMAT 0190-19980 O2 Lot of 3

Celerity AAPGD40W1 Mass Flow Controller IN3XP AMAT 0190-19977 HC1 Lot of 3

Celerity AAPGD40W1 Mass Flow Controller IN3XP AMAT 0190-19977 N2 Lot of 3

Celerity AARGD40W1 Mass Flow Controller IN3XP 439-858 SCCM N2 Lot of 3

Celerity AAXGDD0W1 Mass Flow Controller IN3XP AMAT 0190-26980 New

Celerity AAPGD40W1 Mass Flow Controller IN3XP AMAT 0190-19977 CO Lot of 3

Celerity AASGD40W1 Mass Flow Controller IN3XP AMAT 0190-19979 New

Millipore FSEGD1000R00 Mass Flow Controller AMAT 3030-00822 Refurbished

Millipore FSCGD100B600 Mass Flow Controller AMAT 3030-03091 Refurbished

Celerity AARGD40W1 Mass Flow Controller AMAT 0190-19978 Refurbished

Millipore FSEGD100FF00 Mass Flow Controller AMAT 3030-00830 Refurbished

Celerity AASGD40W1 Mass Flow Controller AMAT 0190-19979 2188 SCCM Refurbished

Millipore FSDGD1001700 Mass Flow Controller AMAT 3030-00838 Refurbished

Mykrolis DSTAD10W Mass Flow Controller AMAT 0190-16730 Refurbished

Celerity DSNRD100 Mass Flow Controller AMAT 3030-13509 150 SCCM Ar Refurbished

Celerity DSNAE1XM Mass Flow Controller AMAT 3030-14215 Refurbished

Celerity DSNAD10W Mass Flow Controller AMAT 0190-14624 Refurbished

Celerity DSMAE1XM Mass Flow Controller AMAT 3030-14214 20 SCCM SF6 Refurbished

Mykrolis DSWGD10W Mass Flow Controller AMAT 0190-16480 Refurbished

Mykrolis DSTAD100 Mass Flow Controller AMAT 3030-14066 Refurbished

Celerity DSKRD100 Mass Flow Controller AMAT 0190-19973 Refurbished

Mykrolis DSRGD100 Mass Flow Controller 200 SCCM C2F6 Refurbished

Celerity DSVBD1XM Mass Flow Controller AMAT 3030-14249 Refurbished

Mykrolis FSDAE100DQ05 Mass Flow Controller AMAT 3030-03753 Refurbished

Celerity DSVAE100 Mass Flow Controller AMAT 3030-14375 Refurbished

Celerity DSVAD10W Mass Flow Controller AMAT 0190-15154 Refurbished

Mykrolis FSDGD100CK00 Mass Flow Controller AMAT 3030-00835 Refurbished

Mykrolis DSSAD10W Mass Flow Controller AMAT 0190-14628 Refurbished

Mykrolis FSDAE100JS05 Mass Flow Controller AMAT 3030-03693 Refurbished

Millipore FSDAE100HM05 Mass Flow Controller AMAT 3030-03693 Refurbished

Millipore FM-3950MEP5-4V Mass Flow Controller AMAT 3030-11212 Refurbished

Celerity DSLAE1XM Mass Flow Controller AMAT 3030-14209 Refurbished

Mykrolis DSYLK2B1 Mass Flow Controller AMAT 3030-14065 Refurbished

Celerity DSYYK2B1 Mass Flow Controller AMAT 3030-14065 Refurbished

Millipore FSCGD100LH00 Mass Flow Controller AMAT 3030-10367 Refurbished

Mykrolis DSWAE100 Mass Flow Controller 30 SLM N2 Refurbished

Celerity DSMRD100 Mass Flow Controller AMAT 3030-12951 Refurbished

Celerity DSPRD100 Mass Flow Controller AMAT 3030-12891 Refurbished

Millipore FSCAE1000T05 Mass Flow Controller AMAT 3030-03698 Refurbished

Mykrolis FSDAE100CT05 Mass Flow Controller AMAT 3030-11780 Refurbished

Millipore FSCAE100H805 Mass Flow Controller AMAT 3030-03695 Refurbished

Millipore FSCAE100H800 Mass Flow Controller AMAT 3030-03695 Refurbished

Millipore FSEGD100TS00 Mass Flow Controller AMAT 3030-09726 Refurbished

Millipore FSDAE100AQ05 Mass Flow Controller AMAT 3030-03688 Refurbished

Celerity DSWAD10W Mass Flow Controller AMAT 0190-14620 Refurbished

Millipore FSEGD100DM05 Mass Flow Controller AMAT 3030-07927 Refurbished

Celerity DSMAD100 Mass Flow Controller AMAT 0190-22632 Refurbished

Celerity DSNRD100 Mass Flow Controller AMAT 3030-12892 Refurbished

Brooks 6256SCZVCLDC Mass Flow Controller 6256S AMAT 3030-12019 Refurbished

Millipore FSDGD100CE00 Mass Flow Controller AMAT 3030-00828 Refurbished

Mykrolis DSYLD100 Mass Flow Controller AMAT 3030-12144 Refurbished

Mykrolis DSKRD100 Mass Flow Controller AMAT 3030-12898 Refurbished

Millipore FSCGD100FC00 Mass Flow Controller AMAT 3030-00827 Refurbished

Celerity DSNRD100 Mass Flow Controller AMAT 3030-12153 Refurbished

Millipore FSCGD100CG00 Mass Flow Controller AMAT 3030-00826 Refurbished

Celerity GF152C-870432 Mass Flow Controller GF125C New

Horiba STEC LF-F20M-A-EVD Liquid Mass Flow Meter AMAT 3030-15253 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-11297 New

Mykrolis MFC Mass Flow Controller AAPGD40W13007 0190-19977 N2 438SCCM New

Celerity IFC-125C Mass Flow Controller AMAT 0190-19317 MultiFlo SC24 New

Millipore MFC Mass Flow Controller FSFGD100BL00 FSDGD100V00 Lot of 3 AS-IS

Celerity MFC Mass Flow Controller IFC-125C Lot of 3 Untested AS-IS

MKS Instruments 640A21TW1VA2V Adaptive Pressure Controller AMAT 3920-00385 New

Celerity UFC-8165 Mass Flow Controller Unit 8165 AMAT 0190-26357 New

Horiba STEC LF-F40M-A-EVD Mass Flow Controller AMAT 3030-14963 New

Horiba STEC LF-F30M-A-EVD Liquid Mass Flow Meter TEPO 25g/min AMAT 3030-14962

Unit UFC-8565 Mass Flow Controller MFloSC18 30SLM AMAT 810-25601 new

Celerity IFC-125C Mass Flow Controller AMAT 0010-42177 100 SCCM Ar New

Horiba STEC Liquid Mass Flow Meter LF-F20M-A-EVD-0?63 3030-15269 New

Unit Celerity 8560 MFC Mass Flow Control UFC-8565 1.5L NH3 new 3030-11542

STEC SEC-Z11DWM Mass Flow Controller AMAT 0190-13117 New

MKS Instruments PCA023TR64UT10 Integrated Pressure Controller πPC PC90 New

STEC LF-F404M-A-EVD Liquid Mass Flow Meter TEOS AMAT 0190-38181 New

Horiba STEC LF-A40M-A-EVD Liquid Mass Flow Meter Lot of 3 Used As-Is

SAM SFC480C Mass Flow Controller MO-4V4C2 Lot of 3 Used As-Is

Horiba STEC LF-210A-EVD Liquid Mass Flow Meter AMAT 3030-14337 New Sealed

STEC LF-F404M-A-EVD Liquid Mass Flow Meter AMAT 0190-38168 TEOS 7g/min New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27877 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27878 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27880 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27882 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27881 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0190-27876 New

Aera FCPI980CBAXDIDJ?AA Mass Flow Controller AMAT 0010-44159 New

Unit Instruments UFC-1100 Mass Flow Controller AMAT 3030-01486 New

Tylan FC-2900MEP Mass Flow Controller AMAT 0225-41614 NF3 New

Aera FCPI980CBAXDIDJ?AA Mass Flow Controller AMAT 0015-02993 New

Aera FCPIDN980C-ABA Mass Flow Controller AMAT 0015-03011 New

STEC SEC-7350M Mass Flow Controller AMAT 3030-12277 New

Aera FCPIDN980CBA Mass Flow Controller AMAT 0015-02989 New

Aera FCPI980BAXDIDJA?A Mass Flow Controller AMAT 0190-34221 New

MKS Instruments 0558A-200L-RV-S Mass Flow Controller 400 SLM N2 New

MKS Instruments 649A21T51CAVR-S Pressure Controller AMAT 0227-26700 New

Celerity IFC-125C Mass Flow Controller AMAT 0190-19321 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-12114 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-11300 New

Celerity UFC-8561C Mass Flow Controller AMAT 3030-14235 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-12103 New

Celerity UFC-8565 Mass Flow Controller AMAT 0190-24779 New

Celerity UFC-8165 Mass Flow Controller AMAT 0190-25567 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-12102 New

Celerity UFC-8565 Mass Flow Controller AMAT 3030-11558 New

Celerity UFC-8165 Mass Flow Controller AMAT 0190-26134 New