Rockwell Automation 1771-SDN DeviceNet Scanner Module Installation Instructions - Manual (Page 19)

Publication 1771-IN014B-EN-P - September 2001
DeviceNet Scanner Module Catalog Number 1771-SDN/C 19
Each individual block transfer is independent, but always updates the
same output bytes in the scanner’s memory table. Of the scanner
output words 0 through 61, the word 0 is reserved for the Module
Command Register. Block transfer sizes 1 through 50 update scanner
output words 0 through 49, thus reducing the required BTW time
when 50 or fewer output words are needed. Sizes 51 thru 56 are
illegal and size 64 is used for Explicit Message Program Control. For
more details on Explicit Message Program Control, refer to page 26.
If the scanner receives a BTW of 62 words, then it knows that it
contains the first block of the table. A BTW of 61 words, if necessary,
contains the second block of the table and so on for 60, 59, 58 and 57
words.
You determine the data that is exchanged with a given node on
channel 1 or 2 by creating custom configurations using RSNetworx
software version 2.22 or later. Refer to your RSNetworx documentation
or online help and your 1771-SDN Scanner Configuration Manual
(publication number 1771-6.5.132) for more information on custom
configurations.
Module Command Register
The first word of the BTW downloaded from the PLC-5 to block 62 is
reserved as the module command register. The register is downloaded
with every 1 through 50 and 62 word block transfer write. This
modifies the scanner’s operation.
To execute a command, you set the appropriate bits in the module
command word, then perform a block transfer write to the first block
(the 62 word block) of the scanner output table. When the scanner
receives the command it immediately executes it. You latch bits 0
through 5 in your program to maintain the scanner’s desired state.
Block
Transfer Size
Accessed
Scanner Output
Block
Scanner Output Data Table
62 words Block 62
Word 0 – Module Command Register Word
Words 1–61
61 words Block 61 Words 62–122
60 words Block 60 Words 123–182
59 words Block 59 Words 183–241
58 words Block 58 Words 242–299
57 words Block 57 Words 300–356
1-50 words Block 1-50 Words 0-49
DeviceNet Messages