Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 113)

1 Publication 1747-UM010B-EN-P - September 2003
Chapter
7
RIO Block Transfer
This chapter contains the following information:
•
RIO block transfer theory of operation
•
RIO block transfer general functional overview
•
using BTR/BTW instructions
RIO Block Transfer Theory
of Operation This section provides a conceptual overview of block transfer as it
pertains to SLCs, RIO scanners, and remote devices. For specific
functionality details, refer to the RIO Block Transfer General
Functional Overview section on page 7-5.
What Is RIO Block Transfer?
RIO Block Transfer is a data transfer mechanism that allows you to
control the transfer of up to 64 words of data to or from a remote
device over the Allen-Bradley RIO link. A Block Transfer Read (BTR)
is used when a remote device transfers data to the SLC. A Block
Transfer Write (BTW) is used when an SLC processor writes data to a
remote device.
The diagrams on the following pages illustrate the concepts of how
block transfers occur using an SLC processor, an RIO scanner, and a
remote device. The first diagram illustrates the path a block transfer
follows. The second and third diagrams illustrate in greater detail the
theory of operation of a BTR and a BTW, respectively.