Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 103)

Publication 1747-UM010B-EN-P - September 2003
Module Control and Status Word 6-7
Data Table Control Word
Data Transfer Status Word The Data Transfer Status Word (DTSW) is used in the data table
transfer from primary to the secondary system. Each bit corresponds
to a block in the 1747-BSN module.
When the primary SLC 5/0x writes a new block into the primary
1747-BSN and sets the bit corresponding to this block in DTCW, the
1747-BSN module transfers the block to the secondary backup
module. The 1747-BSN also sets the corresponding bit in DTSW to
advise the SLC 5/0x that the block has been transferred and the block
area is free to transfer a new data block. This bit is held set until the
corresponding bit in DTCW is cleared by the primary processors.
When the secondary 1747-BSN receives a new data block from the
primary system, it writes the block into the M1 area to be read by the
secondary SLC 5/0x and sets its corresponding bit in DTSW to advise
that this new block is ready to read. After reading the block, the
SLC 5/0x must set the corresponding bit in DTHW. Then the 1747-BSN
module clears the bit in DTSW. The figure below shows the meaning
of the bits in this word.
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
14
0
15 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Block # 1
Block # 2
Block # 3
Block # 4
Block # 5
Block # 6
Block # 7
Block # 8
Block # 9
Block # 10
Block # 11
Block # 12
Block # 13
Block # 14
Block # 15
Block # 16
DTCW (M0:s.3410)