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Rockwell Automation 1785-BCM_BEM, D17856.5.4 PLC-5 Backup Communication Module User Manual User Manual

Page 81

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Operating Your PLC-5 Backup System

Chapter 5

5-17

For example, if the primary processor is sending multiple blocks to the
secondary processor, the data that was in block 2 when block 1 was sent may
change by the time block 2 is sent. This is because the ladder program,
which executes asynchronously to block transfer instructions, may have
changed the information in block 2 before it was sent.