Rockwell Automation 6008-SV2R VMEbus remote I/O Scanner - Manual (Page 47)

Chapter
Communicating with Remote I/O
4
4Ć10
Figure 4.6
BlockĆtransfer sequence - sending a request
VME
master
processor
The VME master processor sends a
BT WRITE request to scanner
BT#n
The scanner copies the request parameters and data
into its internal queue. In SVĆcompatible mode, the
scanner can queue as many as 42 blockĆtransfer
requests; in SVĆsuperset mode, the scanner can queue
only one blockĆtransfer request.
scanner
queue
BT#a
BT#b
BT#n
During the adapter scan, the scanner polls each adapter in the scan
list. If a blockĆtransfer is pending for that adapter, the scanner sends a
blockĆtransfer request to the adapter. The scanner doesn't receive or
send the block data until the next scan. The scanner transmits only
one blockĆtransfer request per adapter per scan.
1771 I/O
chassis
adapter
#n
input
modules
output
modules
scanner
BT#n
❶
❷
❸
scan n
The scanner writes a
result code in the
confirmation status word.
See chapters 5 or 6.
Output Image Table
Input Image Table
Operating Status Word
Confirmation Status Word
Command Word
Address Word
BT Tag Word