ISPSoft User Manual Ary[0]@E0 indicates that 2 is added to the device address (D200) assigned to Ary[0], that is, Ary[0]@E0 represents D202, the device address assigned to Ary[2]. If the value in the index register E0 is 6, Ary[0]@E0 represents D206. D206 is not within the range of devices assigned to the array, but this usage is legal. Owing to the fact that the data stored in an index register indicates the offset for an object modified, users have to be more careful when they modify a symbol whose data type is ARRAY with an index register. Please refer to section 6.2.3 for more information about the usage of arrays.
An AH500 series CPU module differs from a DVP series PLC in the use of an index register to modify an operand. Please refer to the following table. *1. In an AH/AS series CPU module, only the E devices are index registers. In a DVP series PLC, the E devices and the F devices are index registers. Please refer to the operation manual for a model for more information. *2. An index register cannot be modified by another index register. For example, E0@E1 is not allowed. As a result, before a symbol is modified by an index register, users have to make sure that the device assigned to the symbol is not an E device or an F device.
Additional remark (a) The data stored in an index register indicates the offset for a device modified. If the system automatically assigns a device to a symbol modified, the use of an index register will cause the program to be executed incorrectly because users do not know which device is assigned to the symbol. 6-18 Application Example AH/AS DVP DVPxxMC Modifying operands MOV 100 VWD@E0 According to instruction According to instruction Do NOT Support Modifying contact or coil LD VBL 0@E0 _ OUT VBL 1@E1 _ Support According to model types Do NOT Support Modifying symbol variable of ARRAY ARY[0]@E0 Support Support Do NOT Support