Scanlab RTC6 PCIe Board - Controlling Stepper Motors; Output Signals

RTC6 boards
Doc. Rev. 1.0.21 en-US
9 Programming Peripheral Interfaces
284
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9.1.5 Controlling Stepper Motors
Output Signals
The signals (ENABLE, DIRECTION and CLOCK) for
controlling up to two stepper motors are outputted
at the “STEPPER MOTOR” socket connector:
• You can appropriately change the ENABLE signal
(to switch motor current on or off) during
initialization by stepper_init and afterward by
stepper_enable or stepper_enable_list.
• The RTC6 PCIe Board generates periodic CLOCK
signal pulses (during reference runs by
stepper_init and set-position movements by
stepper_abs etc.). With each CLOCK pulse, the
stepper motor executes a single step. You can
adjust the CLOCK signal’s pulse period (and
thereby the speed of stepper motor motion)
during initialization by stepper_init and
afterward by stepper_control or
stepper_control_list (the period is specified in
units of 10 µs cycles).
• You can explicitly set the DIRECTION signal (and
thereby the direction of stepper motor motion)
during reference runs by stepper_init. In
contrast, the DIRECTION signal is internally
controlled during set-position movements by
stepper_abs etc.: the signal gets set (to HIGH) if
the next CLOCK pulse (in accordance with the
defined set-position value) would increase the
internal position variable. The DIRECTION signal
also remains set for the cycles between two clock
cycles and even when the stepper motor has
reached its set position. Only upon an actual
change of direction does the DIRECTION signal
correspondingly change in place of a CLOCK
pulse. Here, output of the next CLOCK pulse is
delayed by a full CLOCK pulse period (undefined
truncation of CLOCK pulse periods never occurs).
Notes
• For signal specifications, see Chapter 4.6.7
”STEPPER MOTOR Socket Connector”, page 87.
• For querying signals, see Section ”Querying
Signals and Status Values”, page 286.
• Stepper motor signals are outputted
independently of any executing lists. A
set_end_of_list, pause_list, set_wait,
stop_execution or external stops do not
terminate or pause a forwarding motion.
• For changes of direction or pulse period, the new
values do not become active until an already-
begun period is complete. Thus, pulse intervals
are never be shorter than the currently defined
value. For change of direction, an additional
empty period (without CLOCK pulse) gets
inserted.