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In the CPU configuration for Quantum CPU in Unity Pro, what is the meaning of "Data Storage" and why it is used.

The data storage is used for READ_U_PCMCIA and WRITE_U_PCMCIA function blocks.

Lets say for eg. you configure the Data storage size as 2000 kB then the 2000 kB of data storage represents:

2000 kBytes * 1024 = 2048000 Bytes

Since The READ_U_PCMCIA and WRITE_U_PCMCIA functions are working with word addresses: 

So 2048000 Bytes / 2 = 1024000 Words

Hence Addresses from 0 to 1024000 for the memory card can be used for data storage.
 
In the MAST section of the program, program as follows:
The memory card is connected into slot 0.
The WRITE_U_PCMCIA function writes 10 words to address 10000 on the memory card from %MW100.
The READ_U_PCMCIA reads 10 words from address 10000 on the memory card to %MW110. 

​Representation of WRITE_U_PCMCIA and READ_U_PCMCIA in ST language:
WRITE_U_PCMCIA (0,10000,10,100,Status_write);
READ_U_PCMCIA (0,10000,10,110,Status_read);


Beasically The WRITE_U_PCMCIA function transfers data from the PLC RAM memory to the user memory card archiving zone and The READ_U_PCMCIA function transfers data from the user memory card archiving zone to the PLC RAM memory. The function READ_U_PCMCIA allowss addressing the PLC zone’s beginning to be copied to the PCMCIA card up to 65 535. 
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