Rockwell Automation 1771-QA Stepper Positioning Assembly User Manual - Manual (Page 117)

4–39 Example Programs
Publication 1771-UM002A–EN–P – May 2000
Rungs 45 thru 47
These rungs display the status of axes 1, 2, and 3. Word 150 is
reserved for future use, word 151 is the status word for axis 1, word
152 is the MS position value for axis 1 and word 153 is the LS
position value for axis 1. The relationship applies to words 154-156
(axis 2) and words 157-161 (axis 3).
After the ladder diagram program has been written, the appropriate
move data can be entered in the file-to-file move instructions in
rungs 28-39. This can be done using the data monitor display mode
of the industrial terminal. With PC processor in program mode, place
the cursor on the file-to-file move instruction and press
[DISPLAY][1]. Move data can be conveniently entered in
hexadecimal notation. The equivalency between hexadecimal and
binary must be known when setting bits in control words.
When rungs 34, 35 and 36 undergo a false-to-true transition, the
positioning profile of axes 1, 2 and 3, respectively, begins execution.
As soon as the first moveset (moveset 1) of an axis is transferred to
the stepper controller module, the corresponding moveset status bit
(status word, bit 16) will toggle and cause the next moveset (moveset
0) to be transferred (rung 37, 38 or 39). After an axis has completed
its last move, the moveset sequence can be repeated by another
false-to-true transition of rung 34, 35 or 36.
Commands such as stop, start, reset, initialization preset, jog
forward, jog reverse and offset for any of the axes can be initiated by
enabling the appropriate rung (rungs 1-27). Note that for this 3-axis
example, only one axis can be jogged at a time (rungs 6, 8, 15, 17,
24, 26).
The status information received from the stepper controller module
by read block transfer (rung 40) is buffered by a file-to-file move
instruction (rung 41). The validated data (10 words) is then stored in
words 150-161. Read block transfer data should be buffered when
operating in an environment where electrical noise is present.
As a precautionary measure, if a write block transfer is not done
within 3 seconds, an output is latched on (rung 43). This output can
be used to energize a warning device.
Status information is displayed in rung 45: words 151-153 for axis 1,
words 154-156 for axis 2 and words 157-161 for axis 3. Rung 45
has no effect on program operation.
During debugging of a positioning program, operate the system with
the stepper translator and motor assembly disconnected until any
programming errors and/or system faults have been corrected.
Operational Summary