Rockwell Automation 1771-DB BASIC MODULE - Manual (Page 325)

Chapter
Call Routines 69–127 13
13 -67
2. The PLC processor latches output image table bit 13 to inform the
BASIC module that valid data is available.
PLC Processor
Latches Output
Image Table
Bit 13
BASIC Module
PLC Backplane
PRT2
PRT1
3. The BASIC module sets bit 13 in the input image table to inform the
PLC processor that that block transfer will be performed.
PLC Processor
Set Input Image
Table Bit 13
BASIC Module
PLC Backplane
PRT2
PRT1
4. The BASIC module performs a block transfer to receive the data.
BASIC Module
PRT2
PLC Processor
PLC Backplane
BTW Buffer
Reserved
DATA 2–64
Reserved
5. The PLC processor unlatches bit 13 in the output image table.
PLC Processor
Unlatches Output
Image Table
Bit 13
BASIC Module
PLC Backplane
PRT2
PRT1