Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 174)

Block Transfer
Chapter 14
14-19
1. When rung 3 goes true, bit 014/07 (the block transfer enable bit) is
turned on and block transfer is requested. This latches on storage bit
010/00 in rung 4.
2. Block transfer is enabled during the program scan. The transfer is
performed during an interruption of the next I/O scan. Data from the
module is loaded into words 050-052. When block transfer is
complete, done bit 114/07 is set in the input image table byte. This
indicates block transfer was successfully performed. The processor
then continues with the I/O scan and program scan.
3. During the program scan, rung 1 is true because bit 010/00 is still
latched on. Bit 114/07 (the block transfer done bit) is on because
block transfer was performed. This turns bit 010/02 on. In rung 2,
bit 10/00 is then unlatched.
4. In rung 5, bit 010/02 is still on and a diagnostic bit is examined to
ensure the data read from the module is valid. Assuming the data is
valid, the diagnostic bit is on and the data is transferred from word
050 to 150. In rungs 6 and 7, the data in words 051 and 052 is
transferred to words 151 and 152 if the diagnostic bit is on.
In this chapter, we showed you how to transfer a block of data in one scan.
The next chapter shows you how to perform subroutines at timed intervals.
Chapter Summary