Schneider Electric 840 USE 106 0 Scan Time Increase table below, PLC to CHS Data, Transfer Rate

Theory of 984 HSBY Operation

The normal Hot Standby configuration contains:

In the local rack: power supply (CPS), PLC (CPU), RIO Head (CRP 93x), Hot

Standby module (CHS)

In one remote IO drop equipped with 8 I/O modules, power supply (CPS) and

lremote adapter (CRA)

Only the logic for the scan time evaluation

PLC Scan Times The scan time increase with different PLCs, after adding HSBY, is outlined in the

Scan Time Increase table below.

CPU - HSBY Baseline	Scantime Increase	Languages Supported
Configuration	because of HSBY
CPU x13 0x0x: 1536, 1x: 512, 3x:	~ 25 ms	984 Ladder Logic only
3000, 4x: 1872
CPU 424 020x: 1536, 1x: 512, 3x:	~ 40 ms	984 Ladder Logic only
1212, 4x: 1872
CPU 434 12 / CPU 534 140x:	~ 40 ms	984 Ladder Logic only
1536, 1x: 512, 3x: 512, 4x: 1872

PLC to CHS Data	The investigation of the PLC specific data transfer rate in a Hot Standby system
Transfer Rate	leads to the following results.
	CPU x13 0x	1.6 ms / byte
	CPU 424 02	2.0 ms / byte
	CPU 434 12 /	1.9 ms / byte
	CPU 534 14

State RAM	The following table lists the number of bytes required for reference storage in state
	RAM.
	Coil (0x)	3 bit
	Discrete (1x)	3 bit
	Input Register (3x)	2 bytes
	Holding Register (4x)	2 bytes plus 2 bit

Based on the data shown in the tables above you may forecast the overall scan time of a Hot Standby system once you know how much state RAM is going to be transferred and the time required for a particular logic application to be executed in a standalone system.

34 840 USE 106 00 January 2003