Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 198)

Preface MicroLogix 1000 Programmable Controllers User Manual
11–10
Using SQO
This output instruction steps through the sequencer file whose bits have been set to
control various output devices.
When the rung goes from false-to-true, the instruction increments to the next step
(word) in the sequencer file. Data stored there is transferred through a mask to the
destination address specified in the instruction. Data is written to the destination
word every time the instruction is executed.
The done bit is set when the last word of the sequencer file is transferred. On the
next false-to-true rung transition, the instruction resets the position to step one.
If the position is equal to zero at startup, when you switch the controller from the
program mode to the run mode instruction operation depends on whether the rung is
true or false on the first scan.
•
If true, the instruction transfers the value in step zero.
•
If false, the instruction waits for the first rung transition from false-to-true and
transfers the value in step one.
The bits mask data when reset and pass data when set. The instruction will not
change the value in the destination word unless you set mask bits.
The mask can be fixed or variable. It will be fixed if you enter a hexadecimal code.
It will be variable if you enter an element address or a file address for changing the
mask with each step.