S7-200 analog values (such as temperature or voltage) into 1 Word (16-bit) number. Zone identifier (AI), the length of the data (w) and the bytes of the start address to access these values. Because analog input for 1 Word, and an even number of bytes (for example, 0, 2, 4), must be even-numbered byte address (such as AIW0, AIW2, AIW4) to access these values. Analog input values for read–only data, the actual precision analog conversion is a 12-bit.
Format: AQW [a starting byte address] AIW4