FFXI Haven - #1.
Open systems have been around for decades, but only recently has their value been recognized. The most significant step occurred in 1981 when IBM broke from its corporate tradition and released a personal computer that could use hardware and software from other companies. Since that time IBM lost control of its child, but it has now adopted the open system philosophy as a core business strategy. All of the details of an open system are available for users and developers to use and modify. This has produced very stable, flexible and inexpensive solutions. Controls manufacturers are also moving toward open systems. One such effort involves Devicenet, which is discussed in a later chapter. A troubling trend that you should be aware of is that many manufacturers are mislabeling closed and semi-closed systems as open. An easy acid test for this type of system is the question does the system allow me to choose alternate suppliers for all of the components? If even one component can only be purchased from a single source, the system is not open. When you have a choice you should avoid not-so-open solutions. plc iec61131 -17.2 17.2 IEC 61131 The IEC 1131 standards were developed to be a common and open framework for PLC architecture, agreed to by many standards groups and manufacturers. Easy Access To All Pages 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 |
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