3-25 Programming
Shift Register ANDing (cont’d)
Shift Position
The point in the encoder revolution at which the register shifts data is programmed
through SHIFT POSITION. When programming Shift Position and the On/Off setpoints
for a channel, remember the following:
When a pulse starts at the Shift Position, as
shown here, the pulse will be enabled as soon as
a bit is shifted into the programmed shift count.
Although the output will function normally on this
revolution, a small output spike may occur on the
following revolution as the bit is shifted to the
next shift count.
Don’t Place the Shift Position at the Start of a Pulse
Don’t Let Speed Comp Move a Pulse Onto the Shift Position
(continued)
Machine at
“Zero” Speed
Machine at High RPM
At “Zero” Speed in this example, the output turns on 100 increments after the Shift
Position. However, as the machine accelerates, speed compensation advances the
setpoints until they overlap the Shift Position. This may split the pulse between two
machine cycles. The portion of the pulse following the Shift Position may activate
during one cycle, while the portion ahead of the Shift Position may activate during
the following cycle.
The Channel 91 Window is “edge sensitive” to the signal from Terminal 16. The leading
edge of the signal must appear in the window for a bit to be set in the register.
Shift Register Clear
Energizing Terminal 14 on TB 1, Figure 7, clears all bits from the shift register immedi-
ately.
Output
Channel
On at 220
Off at 290
Shift
Position
220
0
500
Output
Channel
On at 200
Off at 270
Shift
Position
100
0
500
Shift
Position
100
0
500
Setpoints Advanced
By Speed Comp
