Scanlab RTC 5 PC Interface Board - get_value

RTC
®
5 PC Interface Board
Rev. 1.9 e
10 Commands And Functions
291
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Ctrl Command get_value
Function returns the current value of the specified signal
Call
Value = get_value( Signal )
Parameter Signal desired signal type as an unsigned 32-bit value
Result Current value of the specified signal as a signed 32-bit value
Comments • The selectable signal types are identical to those of the set_trigger command (refer to
the comments there for the allowable value range, signal types and other information).
If the value for
Signal is unallowed, then get_value will not read out a signal and will
return 0 (get_last_error return code
RTC5_PARAM_ERROR ).
• To observe the specified signal over a long time period, use set_trigger to start a corre-
sponding measurement session.
• When using an iDRIVE
®
scan system (intelliSCAN
®
, intelliSCAN
de
®
, intelliDRILL
®
,
intellicube
®
, intelliWELD
®
, varioSCAN
de
), after a reset or power-up of the scan system,
it can take around 5 seconds before valid data starts being returned from the scan
system. If the XY2-100 status word was selected for return transmission, then the oper-
ational readiness can be checked by monitoring bits 4 and 5: bit#4 = 1 and bit#5 = 0
(only) if returned-data transmission is valid.
•For
Signal = 0, get_value returns the current laser status (LASERON signal) even when
list execution has already been finished.
• When you query data returned as status signals from the scan system to the RTC
®
5
(
Status<AX…BY> ), then be mindful of the returned data type’s value range when eval-
uating it (see the command description of control_command):
– Data types originally generated in the scan system as unsigned 16-bit values (e.g. the
XY2-100 status word or the serial number) and returned to the RTC
®
5 as unsigned
20-bit values (whereby bits #0…3 = 0) will contain the relevant information in bits
#4…19. Here, only bits #4…19 should be evaluated (see code example below). For
bits #20…31 of this data type, get_value returns to the PC not only zero, but some-
times (depending on bit #19 of the underlying 16-bit status value) even the value
one. So only evaluate bits #4…19.
– In contrast, data types returned to the RTC
®
5 as signed 20-bit values (e.g. actual
positions or actual speeds) can be safely evaluated as a complete signed 32-bit value
returned via get_value (also see code example below).
– Although Z values must be supplied as a 16 bit values in 3D command parameters,
SCANLAB Z axes and 3-axis scan systems (and correspondingly the get_value com-
mand) return Z values always as signed 20-bit values. If necessary, these returned Z
values must be converted (divided by 16) by the application program.