Rockwell Automation 1769-XXXX Compact I/O Modules - Manual (Page 182)

182 Rockwell Automation Publication 1769-IN088A-EN-P - February 2011
Chapter 3 I/O Memory Mapping
The bits are defined as follows:
• 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.
• CNO = Channel number of the output data being sent. This bit is set by
the PLC controller or other user program to tell the ASCII module which
port’s data is being sent to the ASCII module.
• Reserved bits should be set to 0.
Simultaneous Mode (Two Channels) Input 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.
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
Wo
rd
Bit Position
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Channel 0 Data
0 Tx ID Acknowledged Rx Transaction ID
1 Reserved TG TS ND HE NR RF TF PA RO TO
2 Firmware Revision, Major Firmware Revision, Minor
3 Length (Number of Bytes)
4 Character 1 Character 0
5 Character 3 Character 2
… Character … Character …
x
(1)
Last Character Character …
Wo
rd
Bit Position
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0