Allen-Bradley 1747-SN - RIO Block Transfer General Functional Overview

5–5RIO Block Transfer
Publication 17476.6 - July 1996
The RIO scanner performs block transfers through control/status
buffers that you allocate in the scanner’s M0 and M1 files. For
BTWs, the M0 BT buffer contains BTW control data and BTW data,
while a corresponding M1 BT buffer contains only BTW status
information. For BTRs, the M0 BT buffer contains only BTR
control data, while a corresponding M1 BT buffer contains BTR
status information and BTR data. Block transfers occur
asynchronous to RIO link discrete transfers. Note that block
transfers occur as RIO scan time allows – discrete I/O transfers have
first priority.
A total of 32 block transfer control/status buffers exist in the M0
(output/control) and the M1 (input/status) files. Block transfer
buffers consist of:
• 3 BT control words in an M0 file BT buffer
• 4 BT status words in an M1 file BT buffer
• 64 words of BTW data in an M0 file and 64 words of BTR data in
an M1 file
BT buffers reside on 100 word boundaries in the
M0/M1 files starting at word 100. For example, BT
buffer 1 resides at M0:e.100 and M1:e.100; BT buffer
2 resides at M0:e.200 and M1:e.200; while BT buffer
16 resides at M0:e.1600 and M1:e.1600. Note that
the e" in these examples refers to the physical
chassis slot number in which the scanner resides.
You use an M0 file BT control buffer to initiate
a BT. The corresponding M1 file displays the
status of the block transfer.
M0:e.100
Words
100...109
3 words for
control and
7 reserved
64 words for
BT Write
Data
M1:e.100
4 words for
status and 6
reserved
64 words for
BT Read
Data
M0:e.3200
Words
3200...3209
3 words for
control and
7 reserved
64 words for
BT Write
Data
M1:e.3200
4 words for
status and 6
reserved
64 words for
BT Read
Data
M0 Control Buffers 1 . . . 32
M1 Status Buffers 1 . . . 32
All block transfer buffers (M0 and M1) are cleared
(set to zero) either when the RIO scanner goes
through a power cycle or when the SLC processor
commands the scanner to change mode from
Program to Test mode, Program to Run mode, or
Test to Run mode.
Words
110...173
Words
3210...3273
Words
100...109
Words
3200...3209
Words
110...173
Words
3210...3273
RIO Block Transfer
General Functional
Overview