Scanlab RTC6 PCIe Board - External Start with Track Delay

RTC6 boards
Doc. Rev. 1.0.21 en-US
9 Programming Peripheral Interfaces
292
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External Start with Track Delay
For many applications (for example, if a workpiece
must be initially transported from the light barrier to
the scan system), the start must be delayed with
reference to the triggering start signal.
For this purpose, set_ext_start_delay,
set_ext_start_delay_list or simulate_ext_start
allow configuring a track delay (see (6) in Figure 69)
that postpones execution of a start relative to the
triggering input signal or corresponding command.
The track delay is specified in counting units of an
internal encoder (encoder-counter) that itself can be
triggered by an external or simulated encoder signal,
see Chapter 9.3.3 ”Synchronization by Encoder
Signals”, page 298.
External Starts triggered by an external start signal or
by simulate_ext_start or simulate_ext_start_ctrl
that do not execute immediately because of the track
delay setting are held in a queue that can
accommodate up to 8 starts (each start trigger is
automatically generated when the delay has expired).
This can be useful, for instance, when processing
multiple workpieces transported to the scan system
(even) at irregular intervals: here, up to 8 workpieces
can simultaneously reside within the track delay
(distance between the light barrier and scan system).
If more External Starts are triggered than can be
simultaneously held in the 8-start wait loop, then an
error bit is set, which can be queried by
get_startstop_info ( Bit #11 ). If a track delay is set,
then any previous queue is canceled (see
set_ext_start_delay and simulate_ext_start).
By set_control_mode ( Bit #1 = 1 ) it can be set that
the queue with the external start entries get explicitly
canceled upon an External Stop. With
set_control_mode ( Bit #1 = 0 ) the queue remains
existing after an External Stop.
Notes
• The /START, /START2 and /Slave-START input ports
are edge sensitive (HIGH to LOW level transition).
• The /STOP, /STOP2 and /Slave-STOP input ports are
level sensitive.
• A stop_execution call disables the /START,
/START2 and /Slave-START input ports. An
external stop signal also (at least temporarily)
disables these input ports, that is, as long as one
of the input ports /STOP, /STOP2 or /Slave-STOP is
LOW. set_control_mode can be used to define
whether or not the /START, /START2 and /Slave-
START input ports also stay disabled when the
external stop signal is no longer active.
• s
et_control_mode ad
ditionally allows activation
or deactivation of the input ports /START, /START2
or /Slave-START and deactivation of track delay.
• External Starts are also be suppressed after
pause_list, stop_list or set_wait
(PAUSED list execution status is set). restart_list,
stop_execution, release_wait or an External
Stop ends suppression of the start.
• If list input ports are not yet finished, a buffer
flush should be initiated before an External Start,
for example, by
set_input_pointer( get_input_pointer() ) , so
that any still buffered list commands are fully
transferred to RTC6 List Memory, see
Chapter 6.4.1 ”Loading Lists”, page 105.
• If a master board is started internally (for
example, by execute_list_pos) and subsequently
a slave board by simulate_ext_start, then the
master and slave boards do not run
synchronously if a home jump has been
previously activated by home_position or
home_position_xyz: the home return executes
on the master board before simulate_ext_start
starts the slave board, but executes on the slave
board afterward. While the home return executes
on the slave board, the master board continues
running. This asynchronicity does not occur if all
boards are started by an external start signal (or
by simulate_ext_start or
simulate_ext_start_ctrl) or if no home jump is
activated.