Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS User Manual

Page 137

Advertising
background image

Formatting and Interpreting Data Blocks

Chapter 7

7Ć55

Bit 17 SingleĆStep/Continuous

Bit 17 determines how the 1771-ES expander executes moves when the
run/halt bit is off (run mode):

Single Step - If you turn off this bit, the move ends with deceleration to

zero velocity. If you turn off bit 16 (run command), the axis decelerates
to zero velocity, then continues moveset execution without waiting for
a motion command from the command block. If you turn on bit 16
(halt command), the servo positioning assembly ignores bit 17.

Continuous - If you turn on bit 17 and turn off bit 16, the move blends

smoothly with the next move. That is, the axis accelerates or
decelerates from its final feedrate to the final feedrate of the next move.

Figure 7.35 shows a moveset profile with examples of various bit-16/bit
17 combinations. Table 7.C explains the various combinations with
reference to the figure.

Position Words

Two position words follow the SMCW in each move block. Together,
these words specify an axis motion endpoint, a position preset value, or a
dwell time, depending on the move block type entered in bits 11, 10, and
6 of the SMCW (Figure 7.36).

Advertising