Rockwell Automation 1769-ASCII Compact Module - Manual (Page 16)

16 Compact 1769-ASCII Module
Publication 1769-IN068B-EN-P - May 2005
I/O Memory Mapping
The 1769-ASCII module supports an input assembly that is accessible
through the Assembly Object (Class 4), Instance 101. The input assembly is
up to 108 words. The module supports an output assembly that is accessible
through the Assembly Object (Class 4), Instance 100. The output assembly is
up to 108 words.
Alternate Mode (One Channel at a Time) Output File
Maximum size is shown below. Refer to the Compact I/O 1769-ASCII
Module User Manual, publication 1769-UM012, to use smaller output files.
• Tx = Transmit
• Rx = Receive
• CNI = Channel number of requested input data. This bit is set by the
PLC controller or other user program to tell the ASCII module which
data to produce.
Wo
rd
Bit Position
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 Reserved Tx Transaction ID Ch0
1 Reserved Rx Transaction ID Request Ch0
2 Reserved Tx Transaction ID Ch1
3 Reserved Rx Transaction ID Request Ch1
4 Reserved CNI
5 Reserved CNO
6 Reserved
7 Length (Number of Bytes)
8 Character 1 Character 0
9 Character 3 Character 2
… Character … Character …
106 Character 197 Character 196
107 Character 199 Character 198