Schneider Electric 840 USE 106 0 manual Defining the Transfer Area of State RAM

Using a Quantum 984 HSBY System

Defining the Transfer Area of State RAM

Additional RAM

State RAM dialog

With 984 Hot Standby, you may define additional state RAM (0x, 1x, 3x, and 4x registers) that are transferred in groups over multiple logic scans.

To open the State RAM dialog, deactivate Transfer All State RAM and then use the Options button.State RAM associated with all critical I/O also should be transferred in every scan. Additional state RAM can be grouped and transferred over multiple scans.

Concept shown

State RAM
State RAM
	Transfer:		User Defined
Number of References to Transfer
Coils	(0xxxx):	0		Input Regs	(3xxxx):	0
Discrete Inputs	(1xxxx):	0		Output Regs	(4xxxx):	0
Additional State RAM
Transfer Additional State RAM				Extra Transfer Time	(1-255):	1
Number of References to Transfer
Coils	(0xxxx):	0		Input Regs	(3xxxx):	0
Discrete Inputs	(1xxxx):	0		Output Regs	(4xxxx):	0
OK			Cancel	Help

If you use the CHS instruction to configure the Hot Standby system, you are unable to transfer any more than 12K words, even though the total amount of state RAM could be as much as 64K words. You can limit the number of 4x registers being transferred by selecting a block of registers as part of the nontransfer area, but you cannot limit the number of 0x, 1x, or 3x registers in the transfer area.

Note: The command register must be located in the area of state RAM which is transferred in every scan.

840 USE 106 00 January 2003 97