Rockwell Automation 1771-DCM USER MANUAL 1771-DCM User Manual
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Programming the 1771-DCM
Chapter 6
6Ć5
Example 1:
Suppose you want to transfer six words, and you have configured the
1771–DCM to simulate a 3/4 I/O rack with the following address:
Rack Number = 2, First Module Group = 0. Also, suppose that the
1771–DCM is located in the same chassis with the local processor,
that the 1771–DCM’s actual location (RGS) is 131, that the local
processor’s block transfer read block is 300 through 305, and that the
block transfer write block is 200 through 205.
Data transfers would occur as follows:
Supervisory Processor
To
Local Processor
Output Image Table Words Match the I/O
Chassis Slots Simulated by the
1771-DCM
BTR Instruction Reads Data from the 1771-DCM
into Words 300 through 305
020 Status Word (Zeroed)
021 First Data Word
022 Second Data Word
:
:
025 Fifth Data Word
300 Status Word (Inserted by DCM)
301 First Data Word
302 Second Data Word
:
:
305 Fifth Data Word
Local Processor
To
Supervisory Processor
BTW Instruction Writes Data to the
1771-DCM from Words 200 through
205
Input Image Table Words Match the I/O Chassis
Slots Simulated by the 1771-DCM
200 Status Word (Zeroed)
201 First Data Word
202 Second Data Word
:
:
205 Fifth Data Word
120 Status Word (Inserted by DCM)
121 First Data Word
122 Second Data Word
:
:
125 Fifth Data Word