Rockwell Automation 1761-HHP-B30 MicroLogix 1000 with Hand-Held Programmer (HHP) - Manual (Page 233)

Chapter 13
Using Application Specific Instructions
13–7
•
Destination is the address of the output word or file for a SQO to which
the instruction moves data from its sequencer file.
Important: You can address the mask, source, or destination of a
sequencer instruction as a word or file. If you address it
as a file (using file indicator #), the instruction
automatically steps through the source, mask, or
destination file.
•
Control (SQO, SQC) is the control structure that stores the status byte of
the instruction, the length of the sequencer file, and the current position in
the file. You should not use the control address for any other instruction.
EN DN ER FD
15 13 11 08 00
Length of sequencer file
Position
Word 0
Word 1
Word 2
Status bits of the control structure include:
– Found Bit FD (bit 08) – SQC only. When the status of all
non-masked bits in the source address match those of the
corresponding reference word, the FD bit is set. This bit is assessed
each time the SQC instruction is evaluated while the rung is true.
– Error Bit ER (bit 11) is set when the controller detects a negative
position value, or a negative or zero length value. When the ER bit is
set, the minor error bit (S2) is also set. Both bits must be cleared.
– Done Bit DN (bit 13) is set by the SQO or SQC instruction after it
has operated on the last word in the sequencer file. It is reset on the
next false-to-true rung transition after the rung goes false.
– Enable EN (bit 15) is set by a false-to-true rung transition and
indicates the SQO or SQC instruction is enabled.
•
Length is the number of steps of the sequencer file starting at position 1.
The maximum number you can enter is 104 words. Position 0 is the
startup position. The instruction resets (wraps) to position 1 at each cycle
completion.
•
Position is the word location or step in the sequencer file from/to which
the instruction moves data.
You may use the RES instruction to reset a sequencer. All control bits
(except FD) are reset to zero. The position is also set to zero. Program the
address of your control register in the RES (e.g., R0).
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.
Tip