Omron NT-DRT21, Operation Manual

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6-1 Section Overview of Remote I/O Communications
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Set the input and output areas with the DeviceNet Master Unit’s software
switches or the Configurator.
Master Unit
PC
I/O memory
Allocation
3
Allocation
2 Allocation
1
Automatic I/O
PT memory
within PT
The DeviceNet Interface Unit’s input
and output areas are allocated in the
Master’s I/O memory (work area etc.).
I/O data is transferred automatically so
that the contents are the same.
The DeviceNet Interface Unit’s out-
put area is regularly written to the
area allocated in PT memory and
the contents of the input area are
regularly read.
DeviceNet Interface Unit
Output
area Input
area
PT
Elements
Elements in the PT’s screen are
directly accessed using the PT
memory within the PT.
Output area Input area
Reading PT Status (Input Area Operations)
1, 2, 3... 1. If changes are made to the status or memory tables by PT or other opera-
tions, the changes are mirrored in PT memory.
2. If there are changes in PT memory, the contents are automatically mirrored
in the corresponding input area.
3. The contents of the DeviceNet Interface Unit’s input area are mirrored in the
part of the host’s input area that is allocated to the DeviceNet Interface Unit.
4. The changes in PT status or memory tables can be read from the contents of
the host’s input area.
Controlling the PT (Output Area Operations)
1, 2, 3... 1. Write data in the part of the host’s output area that is allocated to the Device-
Net Interface Unit.
2. Data written to the host’s output area is automatically mirrored in the Device-
Net Interface Unit’s output area.
3. Data in the DeviceNet Interface Unit’s output area is automatically written to
the corresponding part of PT memory.
4. The PT’s display and operation change in accordance with the contents of
PT memory.
The strobe ON time is the length of time that the PT keeps ON the signals which
notify the host (Master) of a change in PT status. The strobe ON time setting con-
trols all three strobes (the screen-switching strobe, numeral-input strobe, and
character-string-input strobe.) Set the strobe ON time with the PT system
menu’s CompoBus/D setting switch.
Each strobe signal is turned OFF automatically after the strobe ON time elapses.
When setting the strobe ON time, be sure that it is longer than the cycle time in
the host’s CPU Unit so that the host (Master) will reliably read changes in the
Precautions for the
Strobe ON Time Setting