Allen-Bradley 1404-M4, User Manual

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Publication 1404-UM001D-EN-E - October 2004
C-6 Sample Applications
PLC-5 Controller Using Remote I/O
The second example also reads and writes the Powermonitor 3000
date and time but using a PLC-5 controller and Remote I/O. In this
example, a Powermonitor 3000 has a logical address of Rack 1, Group
0. The PLC-5 data table files used are the same as in the previous
example. The main difference is that this example uses block transfer
instructions rather than message instructions, and the block transfer
length determines which data table is selected.
The source and destination data tables in the PLC-5 must contain at
least as many words as the block transfer length.
The Read Clock from PM3K and Set Clock from PLC bits are used to
initiate the messages, and are reset when the message instruction
either completes successfully or an error occurs. In your application
code, if the message rungs are controlled programmatically, ensure
that only one message is enabled at a time, and add sufficient time
delays between block transfers to avoid overloading the channel.