Rockwell Automation 20-COMM-R Remote I/O Adapter - Manual (Page 60)

5-2 Using Block Transfer Messaging
20-COMM-R Remote I/O Adapter User Manual
Publication 20COMM-UM004D-EN-P
About Block Transfer
Messaging
Block Transfer messaging is used to transfer data to the drive. The size of
Block Transfer messages to the Remote I/O adapter determines their
purpose.
Block Transfer I/O
For information about Block Transfer I/O messages, see Chapter 4 , Using
Discrete and Block Transfer I/O .
One Block Transfer request is processed per Remote I/O rack scan, but
multiple requests to a rack can be initiated. You can use Block Transfer
Read messages to gather input and status data from the adapter and Block
Transfer Write messages to send output and configuration data to the
adapter and connected drive.
Formatting Block Transfer
Messages
Using Block Transfer to Initiate Explicit Messages
Figure 5.1 Explicit Message Format
Most Significant Byte = bits 15…8
Least Significant Byte = bits 7…0
See Block Transfer Write Structure to Send Block Transfer Messages on
page 5-3 for a description of each word in a Block Transfer Write used to
initiate Explicit Messages.
Words Type Used For See
18 or fewer I/O Reference/Feedback and Datalinks Chapter 4
20, 30, or 60 Explicit Configuring and monitoring data This chapter
Other Not Recognized Do not use or an error will occur. —
Bit 15 0 15 0
Word 0 0x00 Length 0x00 Length
Word 1 DPI Port 0x81 Status Type Status Size
Word 2 0x00 CIP Service Status Information
Word 3 CIP Class Data or Padding
Word 4 CIP Instance
Word 5 CIP Attribute
Word 6 Data or Padding
…
Word 19
(20 word BTW length)
- or -
Word 29
(30 word BTW length)
- or -
Word 59
(60 word BTW length)
Block Transfer Write
Block Transfer Read