Yes you need to do a bit of reading, not just on the data areas but the programming structure. There are also data blocks, which is used to group stored data into a common area. Its always best to assign names to these in the variable area at the start of the block. Within each block you also have Temp memory, where you can assign names to throw away memory, ie store a result which is part way through logic to be used further in the same logic block and will be re assesed from scratch next scan (these can be termed as scratch flags). M flags are internal memory addresses where you may want to store results of logic that you need the next scan. For outputs you have Q, QW and PQW, similar to the inputs. WEhen you create your cards you tell it what addresses to use for the cards. When you create your hardware profile, you create your racks and cards. At the beginning of a scan the periphery values are transferred to the image table and the image table is used in the program for digital addresses, analogues generally use the periphery data. The I/IW Inputs are all an image of the periphery, they are referred to as an image table. PIW = Periphery IW, this is the actual real time value of an input word. I = digital inputs, example I 10.0 IW = Analogue inputs, such as IW250, although you would usually address an analogue as PIW in a standard PLC. You have a number of different types of data and these have a basic level of a Byte (8 bits).
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