Special Data Registers (Sr); Index Register (E); File Registers (Fr) - Delta AS Series Operation Manual

The registers can be classified into three types according to their properties.
1. General-purpose register: when the PLC begins to run or is disconnected, the value in the register
clears to zero. To retain the data when the PLC begins to RUN, refer to the ISPSoft User Manual for more
information. Notice that the value still clears to zero when the PLC is disconnected.
2. Latched register: if the PLC is disconnected, the data in the latched register is not cleared. In other words,
the value before the disconnection is still retained. To clear the data in the latched area, use the RST or
ZRST instruction.
3. Data exchange area: When the PLC is connected with a module, the PLC exchanges data with the
connected module at every scan cycle. And the data is stored in data registers D26000 to D29999. Refer
to the ISPSoft > HWCONFIG > Module > Device Setting > Normal Exchange Area to see the data register
range.

5.2.13 Special Data Registers (SR)

Every special data register has its definition and specific function. Refer to section 2.2.14 in the AS Series
Programming Manual for more information.

5.2.14 Index Register (E)

The index register is a 16-bit data register. Like the general register, you can read data from it and write data
into it. However, it is mainly used as the index register. The index registers range from E0–E9. Refer to section
4.4 in the AS Series Programming Manual for more information about using index registers.

5.2.15 File Registers (FR)

The AS Series PLC provides you with file registers for storing larger numbers of parameters. You can edit,
upload, and download the system parameters with ISPSoft. You can read the values in a file register can be
read while operating the PLC. Refer to the MEMW instruction (API 2303) in the AS Series Programming
Manual for more information about how to write to a file register.
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