3500/61本特利3500/613500/61本特利3500/61
编程需要敢于实践的信心
我曾经教过一个学生学AutoCAD，我对她的*要求就是实践。我告诉她：你随便怎么操作，大不了一张图重画；zui坏的结果是系统崩溃，没关系，系统重做，再来；只要电脑没被砸了，怎么都行。两年后，我再看到她做的CAD图纸，也自叹不如。
同样道理，只有不断地在PLC上运行这些指令，观察运行的结果，才能弄清PLC指令的作用。很多初学者对PLC一脸的迷茫，往往是出于一种畏惧，担心损坏设备。而这些畏惧是没有任何道理的。仔细的阅读手册是非常重要的，但是仅靠读书是成不了一个工程师的。更何况手册上的内容并非面面俱到。我在接触到那些不熟悉的指令时，喜欢单独编一个小程序，让PLC运行。然后逐个修改条件，观察运行的结果（MicroWin为用户提供了非常好的监控手段），反过来再重新理解手册的描述，这样就可以非常直观的理解这些指令的作用和使用方法。不必担心自己写的程序会有什么问题，会影响PLC的正常工作。程序有没有问题，只有让PLC运行了才能发现。而发现问题并解决问题就是对自己能力的提高。撇开硬件操作不谈，单就软件来说，我还真没有遇到过由于软件问题而损坏PLC的事。在这里不必担心继电器电路接错线可能造成的后果。所以，大胆的实践是PLC编程的必由之路。
当然，大胆实践并不是野蛮操作，而是必须遵循必要的规范。还有一个要注意的，在程序未经可靠性证实之前，千万不要挂接负载，以免造成不必要的损失。数字量的输出有LED显示；而模拟量处理可以采用一些硬件或软件模拟手段来解决。
郑娟萍
厦门仲鑫航自动化设备有限公司
编程需要有缜密的逻辑思维
编程本身就是一种逻辑思维过程。在高级语言中，使用zui多的是if then else、select这些条件判别语句，这就是逻辑中的因果关系。PLC程序就是由这些因果关系组成的：判别条件是否成立，进而决定执行相应的指令。zui初的PLC是用来替代继电器逻辑电路的，所以继承了继电器电路以触点作为触发条件的描述方式。在PLC中，以虚拟触点代替了继电器的金属触点，而继电器电路所表达的逻辑关系还是被完整的保留下来。即使引入了继电器电路难以胜任的数值处理过程，PLC从根本上还是在执行一个个因果关系。所以，理顺对象的各个事件之间的逻辑关系，是编程之前必须精心做好的准备工作。我在接到一项任务后，*件事就是整理出一份逻辑关系图，与用户反复商讨，取得用户的认可，然后才真正进入程序的编写过程。
Steren 200-033 RG6 Quad Shield Coaxial Cable Crimp F Connector (Pack of 100)
GEM Electronics 301-4 2-Piece BNC Crimp Connector (Pack of 37)
GEM Electronics 301-4 2-Piece BNC Crimp Connector (Pack of 33)
Weltron 44-285-6 RG-6 BNC Male Cable Connector (Pack of 18)
Weltron 44-135 75 Ohm F Plug Terminator (Pack of 15)
Ideal Industries, Inc. IA-3634 RG-6 BNC Plug
Cambridge Products Corp. CP8810 RGTFE-59 BNC Crimp Connector (Pack of 15)
WAGO 873-PA66 Lumi-Nuts Pushwire Connector for Luminaire Disconnect (NNB)
F-Conn Industries DB59U RG59 / 59 Quad DB F Connector (Pack of 19)
F-Conn Industries DB6U RG6 / 6 Quad F Connector (Pack of 18)
F-Conn Industries DB59 RCAU Connector (Pack of 10)
Wiremold 5790B Armored Cable Connector (Pack of 2)
WAGO 873-PA66 Lumi-Nuts Pushwire Connector for Luminaire Disconnect
Allen Products, Inc. CT 732 RG-6 Male CATV Connector (Pack of 4)
Wiremold 5781A 3/4" Box Connector (Pack of 2)
Allen Products, Inc. CT 732 RG-6 Male CATV Connector (Pack of 5)
Wiremold 817 800 Series Internal Elbow
Allen Products, Inc. CT 722 Die Cast Mounting Block with Screws (Pack of 2)
Allen Products, Inc. CT 721 Female 3/4" In-Line Splice (Pack of 2)
Wiremold 5782 Conduit Connector (Pack of 2)
Allen Products, Inc. GBNC58-H 50 Ohm BNC Hex-Crimp Connector (Pack of 2)
Wiremold V518 V500 Raceway External Elbow (Box of 5)
Wiremold 4001DA Surface Metal Raceway Divider Clip (Box of 4)
Wiremold V517 V500 Raceway Internal Elbow (Box of 4)
Spears AX1J3 Bulkhead Tank Fitting 1/2"
tyco 179935-000 Multiple Entry Connection Kit
United Electric SD6213-27 Brass Bushing Kit
Electroline L660-1 Two-Hole EMT Strap (Box of 50)
Hubbell RACO 3410 2-1/2" Liquid-Tight Straight Connnector
Electroline L660-1 Two-Hole EMT Strap (Box of 49)
Walker Parkersburg Textron 500T Single Low Tension Plate
T&B Liquid-Tight 3/8" Fitting 90 Degree
T&B 3/8" Liquid-Tight Fitting 90 Degree
Appleton 3/8" Fitting 90 Degree
Appleton Fitting 3/8" 90 Degree
T&B Liquid-Tight 1" Fitting 90 Degree
T&B 1" Liquid-Tight Fitting 90 Degree
O-Z/Gedney 3/8" Liquid-Tight Fitting 45 Degree
O-Z/Gedney Liquid-Tight 3/8" Fitting 45 Degree
RACO 3/8" Liquid-Tight Fitting 45 Degree
RACO Liquid-Tight 3/8" Fitting 45 Degree
T&B Liquid-Tight Fitting 3/4" Straight
T&B 3/4" Liquid-Tight Fitting Straight
Hubbell 3/4" Liquid-Tight Fitting Straight
Hubbell Liquid-Tight 3/4" Fitting Straight
Appleton ST-100 Steel Connector 1" (Box of 6)
Appleton 3/4" Fitting 90 Degree
Appleton Fitting 3/4" 90 Degree
Appleton Fitting 3/4" Straight
Liquid-Tight Fitting 1" Straight
Appleton 3/4" Fitting Straight
1" Liquid-Tight Fitting Straight
Appleton ST-9038 ST Series Connector 3/8" (Box of 50)
O-Z/Gedney 4Q-938 Liquidtight Connector (Box of 13)
Bryant Electric, Inc. BDS85L Cable Grip 0.85"-1.0"
Hubbell 07310005 Kellems Grip 0.850"-1.000"
Hubbell 07310004 Kellems Grip 0.730"-0.850"
Hubbell 074-09-3403 Kellems Grip
Hubbell SR-040 Kellems Grip 0.40"-0.54"
T&B Cable Grip 1/2"
T&B Cable Grip 3/4"
Hubbell 073-03-1201 Kellems Grip 0.32"-0.43"
Hubbell 073-03-1204 Kellems Grip 0.73"-0.97"
Hubbell 1/2F1 Cord Connector
RACO 1 1/2" Liquid-Tight Fitting Straight
MW 3/4" Fitting 45 Degree
Appleton 1/2" Fitting 90 Degree
3/8" Liquid-Tight Fitting 45 Degree
Appleton 2" Fitting Straight
Appleton 1 1/2" Fitting 90 Degree
O-Z/Gedney 4Q-9125 1 1/4" Liquid-Tight Fitting 90 Degree
O-Z/Gedney 4Q-9100 1" Liquid-Tight Fitting 90 Degree
O-Z/Gedney 1/2" Liquid-Tight Fitting 45 Degree
RACO 3/4" Liquid-Tight Fitting 90 Degree
T&B 1 1/4" Liquid-Tight Fitting 90 Degree
Appleton 1" Fitting Straight
O-Z/Gedney 3/8" Liquid-Tight Fitting 90 Degree
O-Z/Gedney 3/4" Liquid-Tight Fitting 45 Degree
Appleton 1/2" Fitting 45 Degree
T&B 1 1/4" Fitting 90 Degree
MW 3/8" Liquid-Tight Fitting 45 Degree
Gould Efcor 1" Liquid-Tight Fitting 90 Degree
13-50 1/2" Liquid-Tight Fitting 45 Degree
1/2" Liquid-Tight Fitting 45 Degree
Ideal 3/4" Liquid-Tight Fitting 90 Degree
Hubbell 1/2F2 1/2" Liquid-Tight Fitting 90 Degree
Lapp Kabel 1/2-NPT 1/2" Skintop liquid-Tight Connector Straight Black
MW 3" Fitting Straight
Appleton 1 1/4" Fitting 45 Degree
12-75 3/4" Liquid-Tight Fitting 90 Degree
RACO 1" Liquid-Tight Fitting 90 Degree
Appleton 2" Fitting 90 Degree
T&B 2" Liquid-Tight Fitting 90 Degree
MW 1" Liquid-Tight Fitting Straight
O-Z/Gedney 1" Liquid-Tight Fitting Straight
Appleton EGS CG3138 Aluminum Cord Connector 3/8"
Steel City 1/2" Fitting Straight
Steel City 2 1/2" Fitting Straight
Appleton 3/4" Liquid-Tight Fitting Straight
ETP 3/8" Liquid-Tight Fitting 45 Degree
1" Fitting Straight
3/8" Liquid-Tight Fitting Straight
Halex 42-4 1 1/2" Fitting Straight
EMC LSC-18 1 1/4" Fitting Straight
T&B 1" Fitting 90 Degree
1 1/4" Liquid-Tight Fitting 90 Degree
Appleton 1 1/4" Fitting Straight
O-Z/Gedney 3/4" Liquid-Tight Fitting Straight
T&B 1 1/4" Liquid-Tight Fitting Straight
Madison IL 110 Armored Cable Connector 3/8"
T&B 1/2" Liquid-Tight Fitting 45 Degree
T&B 3/8" Liquid-Tight Fitting 45 Degree
Appleton ST-9038 Mall Iron Connector 3/8" (Box of 25)
RACO 3543 Liquid-Tight Connector 3/4" (Box of 12)
Efcor 13-50 Liquid Tite Connector 1/2" (Box of 8)
Appleton ST-90100 Mall Iron Connector 1" (Box of 7)
ETP LQ 3845 Liquid-Tight Connector 3/8" (Box of 12)
Madison IL 110 Armored Cable Connector 3/8" (Box of 50)
Amphenol 31-71000-RFX Crimp Plug
Bridgeport 412-DC2 Squeeze Connector 1 1/4" (Box of 10)
T&B Fittings 5343 Liquidtight Conduit Connector 8-Pack
Neer EGS LMM-11 Liquidtight Conduit Connector 20-Pack
Neer EGS GC-100 Screw-In Connector (Box of 25)
Neer EGS LMM-11 Liquidtight Conduit Connector 25-Pack
Appleton EGS CG3138 Aluminum Cord Connector (Box of 25)
O-Z/Gedney 4Q-938 Liquidtight Connector (Box of 15)
O-Z/Gedney 4Q-9125 Liquidtight Connector (Box of 5)
O-Z/Gedney 4Q-975 Liquidtight Connector (Box of 10)
O-Z/Gedney 4Q-75 Liquidtight Connector (Box of 10)
O-Z/Gedney 4Q-9100 Liquidtight Connector (Box of 3)
Appleton ST-9038 Liquidtight Connector (Box of 25)
Eaton Weatherhead C5216X6X6 Fitting
ILSCO D1112 Lug AU-0 1/0-14 AL9CU
Foster Manufacturing H6 Hydraulic Disconnect Coupling
Maska L-099X7/8 Half Coupling with L-099X3/4
Wiremold RPD-2CA Walkermed Electrical Raceway Bracket 9
Wiremold RPD-2CA Walkermed Electrical Raceway Bracket20
Process Technology of Penn.Inc. 40-B Bellows Steam Trap
1/8 NPT 90 Degree Elbow Male/Female Fitting
Hubbell BSP25 "D" Subminature Connector
Crouse-Hinds CGE295 Male Thread Cord and Cable Fitting 3/4"
IR ARO 4TR75 CSN6-G Connector Strain Relief 16MM
