Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 149)

Publication 1747-UM010B-EN-P - September 2003
Programming Techniques 9-7
0016
B3:3
15
COP
Copy File
Source #M1:1.5420
Dest
#N19:128
Length 128
COP
B3:4
15
0017
MOV
Move
Source
B3:4
0010000001000000<
Dest
M0:1.3411
?<
MOV
0018 END
This rung copies the "new" Data Block #16 data from the secondary 1747-BSN to a file within the secondary processor. When the Copy is
complete, the DTHW (Data Table Handshake Word) bit for Data Block #16 (B3:4/15 = M0:1.3411/15) must be set to inform the secondary
1747-BSN that the secondary processor has received the latest Data Block and is now ready for the next block of data via Data Block #16.
This rung copies the virtual DTHW word (B3:4) to the actual DTHW word (M0:1/3411) located in the 1747-BSN module. M-file accesses are
interrupts to the processor. Using virtual words minimizes M-file accesses, thereby minimizing the effects of these transfers on the ladder
program scan time.
Virtual DTHW bit for Data Block #16
Virtual and Actual DTHW words
Virtual DTSW bit for Data Block #16