Enter a relay used to accept signals from external sensors or switches are special registers of the input image. It can only be driven by external signal driver. At the beginning of each scan cycle, CPU total physical input is sampled and sampled values written to the input register. Enter the relays generally used an octal number, a Terminal occupies a point. It has 4 addressing modes that can be bit, byte, Word or double word to access the input process image data in the registers.
section : I (bytes address]. [–Address) such as: I0.1
Byte, Word or double word:][I[length a starting byte address] such as IB3 IW4 ID0