Difference between Process Image and Number Of IOs

Hi firends ,

As i am checking in siemens 300 specification sheet there are 2 terms

• Process Image
  
• Number Of IOs
• 
  

as i Know both are same , Is any difference between them ? . Kindly Explain

Regards

Manish

Hello MANISH CHOUDHARI,

The process image will be read in at the beginning of the CPU cycle. And during program exicution the I/O will be read from Process image.

At the end of the CPU cycle, the Process image is copied to the outputs. (At the end of your program you will be writing to outputs)

Adresses outside the process image will not be read in standard. You can read them in your program by using PIW or write by using PQW. (instead of IW and QW) (When you use PIW the input word is read direct from card)

Most times your digital I/O is placed inside Process Image and your analog I/O is placed outside Process image

How bigger the Process Image, it will reduce your memory of CPU for program

Best regards,

Wizard

Hi Wizard,

Thanks You for resolving my query ..

Regards

Manish