Rockwell Automation 1785 PLC-5 User Manual download pdf (Page 88)

1785-UM022C-EN-P - February 2008

4-8

An IDO is initiated that updates the private memory output buffer

from the source file before the next normal output-image update. The

Data File Offset (175) is the offset into the buffer where the data is

stored. The Length (24) identifies the number of words in the transfer

or a logical address that specifies the number of words to be

transferred. The Source (N12:175) is the source of the words to be

transferred. The Source should be the matching data table address in

the DOF except when you use the instruction to ensure data-block

integrity in the case of Selectable Timed Interrupts (STIs). See Using

Selectable Timed Interrupts with a Program

on a ControlNet Network on page 4-9

For more detailed information about writing ladder programs and

programming ControlNet I/O transfers using Immediate Input (IIN)

and Immediate Output (IOT) instructions, see your programming

software documentation.

IDO

IMMEDIATE DATA OUTPUT

Data file offset

Length

Source

IDO instruction

copies from the

data table to the

private

DOF buffer

Outputs transmitted

to the ControlNet

network on next

opportunity

N12:175 175

N12:0 0

Data Table

Private DOF Buffer

175

N12:175

1 2 ... 83 84 85 86 87 88 89 90 91 92 93 ... 147 148

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Rockwell Automation 1785 PLC-5 User Manual Page 88