Rockwell Automation 2711-ND3 PanelBuilder v2.60 Software User Manual - Manual (Page 69)

4–13 Communications Overview
Publication 2711-6.0
Helpful Hints for Block Transfers
•
Read and write blocks can use the same addresses.
•
Read and Write Blocks may overlap partially or completely.
•
Improve response times by compacting the data into the fewest
possible blocks (no unused bits) or keep all data for a screen in a
single block. Remote I/O scanners generally perform one block
transfer in a single I/O scan.
•
Ladder logic can use the PanelView’s current screen tag (status
tag) to enable block transfers as necessary. The screen data is
automatically updated when an operator selects the screen. See
Chapter 20 for a description of the status tags.
•
Minimize the number of block transfers.
Block Transfer Read Example
The following example illustrates a block transfer read. The
PanelView terminal is assigned to rack #3, starting module group 0.
One of the PanelView objects, a numeric entry display addressed as
N7:2, writes to a part of the data block being transferred.
BLOCK TRANSFER READ
Rack
03
Group 0
Module 0
Control Block N36:0
Data File N7:2
Length 4
Continuous N
➀ The operator enters the data into the numeric
entry display.
➁ Using information in the Block Transfer dialog,
the PanelView determines the position of the
data and the block size.
Numeric Entry Cursor Point with
Tag Name = Motor_Speed
Tag Address = N7:2
➂ The PanelView terminal places the data in the
first word of a 4 word block.
➃ The PLC reads the 4 word block of data and
stores it at the Data File address.
BTR
(EN)
➄ The value entered on the PanelView is now
stored at N7: 2 = 123.
Read From
PanelView
Data To PLC
Word 1 123
Word 2
Word 3
Word 4
1 2 3