Only device names defined in the device access API can specify the index of symbols. The index specification of symbol is used to specify an address offset using brackets [] after the symbol name as shown below. The device address is incremented by the specified numeric value multiplied by the size of the symbol data type.
(Symbol name)[Numeric Value]
For example, Valve[2]
If a symbol "valve" is assigned to D100 and is signed 16-bit, it indicates D102. If it is assigned to D100 and is unsigned 32-bit, it indicates D104.