Allen-Bradley 1756-CNB User Manual

Publication 1756-UM523F-EN-P - December 2006
Configure and Program the Controller 75
Actions
Action Details
1. Get the size of your crossload data. Use a Get System Value (GSV) instruction to read the REDUNDANCY object.
See Logix5000 Controllers General Instructions Reference Manual, publication
1756-RM003, for more information on the GSV and SSV instructions.
2. Estimate the crossload time. Which controller do you have?
• If ControlLogix5555, then crossload time = (0.0015 ms * DINTs) + 1 ms overhead
• If ControlLogix5561, then crossload time = (0.0013 ms * DINTs) + 1 ms overhead
• If ControlLogix5562, then crossload time = (0.0013 ms * DINTs) + 1 ms overhead
• If ControlLogix5563, then crossload time = (0.0013 ms * DINTs) + 1 ms overhead
where DINTs is the size of tag data to be crossloaded, measured in 4-byte words.
For this information Get this attribute Data
Type
Description
• Size of the last crossload
• Size of the last crossload
if you had a secondary
chassis
LastDataTransfer
Size
DINT This attribute gives the size of data that was or would have been
crossloaded in the last scan.
• The size in DINTs (4-byte words).
• You must configure the controller for redundancy.
• You do not need a secondary chassis.
Is there a synchronized secondary chassis?
• Yes — This gives number of DINTs that was crossloaded in the last
scan.
• No — This gives number of DINTs that would have been crossloaded
in the last scan.
• Size of the biggest
crossload
• Size of the biggest
crossload if you had a
secondary chassis
MaxDataTransfer
Size
DINT This attribute gives the biggest size of the LastDataTransfer Size
attribute.
• The size in DINTs (4-byte words).
• You must configure the controller for redundancy.
• You do not need a secondary chassis.
• To reset this value, use an SSV instruction with a Source value of 0.
Is there a synchronized secondary chassis?
• Yes — This gives biggest number of DINTs that was crossloaded.
• No — This gives biggest number of DINTs that would have been
crossloaded.

Allen-Bradley 1756-CNB Specifications

General

Brand	Allen-Bradley
Model	1756-CNB
Category	Control Systems
Language	English