Rockwell Automation 20-COMM-R Remote I/O Adapter - Manual (Page 64)

5-6 Using Block Transfer Messaging
20-COMM-R Remote I/O Adapter User Manual
Publication 20COMM-UM004D-EN-P
The following table describes the main events and what a program is
monitoring when performing Block Transfer messaging.
3. Receive data from the program.
After the program with Block Transfer messages has been run, the
results can be seen in a data file. The data file that is used depends on
your controller and application.
Example Programs The example ladder logic programs ( Figure 5.3 , Figure 5.4 , and Figure 5.6 )
can be used to demonstrate how Block Transfer can be used to send Explicit
Messages from a ControlLogix, PLC or SLC controller, respectively. With
these examples, Block Transfer messaging is used to read or write a
parameter value from a PowerFlex 70 drive at Rack 1, Group 0, Slot 0.
These example ladder programs are continuations of the Discrete and Block
Transfer I/O example ladder programs in
Chapter 4 . The ‘Main Routine’
ladder logic in that chapter performs Jump to Subroutines (JSRs) to these
examples.
Item Event Description
➊ BTW Request Before initiating a Block Transfer message, bit 8 must be 1. This
setting indicates that the adapter and drive are communicating, so
a Block Transfer message will reach the drive.
Before initiating a Block Transfer Write message, bit 9 must be 1.
This setting indicates that a Block Transfer Write can be executed.
➋ BTW Data at
Adapter
Because only one Block Transfer message can be active at a time,
bit 9 is set to 0 when the Block Transfer Write begins. Bit 9 and bit
10 remain at zero while the Block Transfer is being processed.
➌ BTW Complete When the Block Transfer is complete, bit 9 and bit 10 are set to 1.
This setting indicates that the program can perform either a Block
Transfer Read or a Block Transfer Write.
Bit 11 remains at 0 if messaging is successful. If an error occurs, it
would be set to 1.
➍ BTR Request Before initiating a Block Transfer Read message, bit 10 must be set
to 1. This setting indicates that data is available to read. When the
message is executed, bit 9 and bit 10 are set to 0 because only
one Block Transfer can be active at a time.