Schneider Electric 840 USE 106 0 manual State RAM Transfer and Scan Time

Theory of 984 HSBY Operation

The State RAM Transfer and Scan Time

Reduce Scan This section describes manipulating the state RAM transfer to reduce scan time

Time

Note: The state RAM transfer area contains all the state RAM values that are passed between the Primary and Standby controllers. The size of the transfer area may be as large as the total size of your controller’s state RAM or a portion containing critical I/O reference data types.

As the simplified block diagram below shows, all 0x references in the state RAM transfer area are transferred first, then all 1x references, followed by all the 3x references, and finally all the 4x references:

Total number of discrete outputs transferred

Total number of discrete inputs transferred

Total number of register inputs transferred

0nnnnn

1nnnnn	Where nnnnn is a
	multiple of 16

3nnnnn

Total number of register outputs transferred

4nnnnn

36 840 USE 106 00 January 2003