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<< Click to Display Table of Contents >> Differences between Conventional devices, PLC's and Cables |
  
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<< Click to Display Table of Contents >> Differences between Conventional devices, PLC's and Cables |
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The same parts are available to assemble the composition of item designations for all three device types that are discussed here. Terminals, which are discussed elsewhere, is however different in that regard.
Despite that, there are however some practical differences that are discussed here.
•Conventional devices are simply devices that are not terminals, connectors, PLC's or cables.
•The PLC device type and the corresponding set of symbols with main symbols, help symbols and mirror symbols, are somewhat different from conventional devices. Among those differences are the fact that PLC help symbols (I/O symbols) may have attributes for I/O numbers, symbolic addresses and up to seven additional texts. PLC mirrors also support mirroring the information from all those attributes.
Another important difference, is that the composition of item designations for PLC's is separated from conventional devices. This means that a PLC help symbol can never interact with for example a conventional main symbol. PLC help symbols only interact with PLC main symbols and PLC mirrors. Even if the item designations would be identical, symbols for different device types of can never interact with each other.
•The Cables device type and the corresponding set of symbols with main symbols, help symbols and mirror symbols, are quite similar to conventional devices, but there are some fundamental differences here too. Among those differences are the fact that a cable does not have a single location in the same way as a conventional device has. Typically, a cable has two ends, which often are located in two different locations. For cables, it is therefore common to omit the location part of the item designation and only include function and/or product aspects. In other words, a typical item designation composition for cables consists of plant, component type and counting number.
For reasons discussed above, the composition of item designations for cables is separated from conventional devices. This means that a cable help symbol can never interact with for example a conventional main symbol. Cable help symbols only interact with cable main symbols and cable mirrors. Even if the item designations would be identical, symbols for different device types of can never interact with each other.