Scanlab RTC6 PCIe Board - Page 443

RTC6 boards
Doc. Rev. 1.0.21 en-US
10 RTC6 Commands
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Ctrl Command get_value
Function Returns the current value of the specified signal.
Call Value = get_value( Signal )
Parameters 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 set_trigger (refer to the comments
there for the allowed value range, signal types and other information). If the value for
Signal is unallowed, then get_value does not read out a signal and returns 0
(get_last_error return code RTC6_PARAM_ERROR ).
• To observe the specified signal over a long time period, use set_trigger to start a
corresponding measurement session.
• When using an iDRIVE scan system (see Glossary entry on page 27), 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.
• 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 RTC6
( Status<AX…BY> ), then be mindful of the returned data type’s value range when
evaluating it (see control_command):
– Data types originally generated in the scan system as unsigned 16-bit values (for
example, the XY2-100 status word or the serial number) and returned to the RTC6
as unsigned 20-bit values (whereby Bit #0…Bit #3 = 0) contain the relevant
information in Bit #4…Bit #19. Here, only Bit #4…Bit #19 should be evaluated (see
code example below). For Bit #20…Bit #31 of this data type, get_value returns to
the PC not only zero, but (depending on Bit #19 of the underlying 16-bit status
value) even the value one. So only evaluate Bit #4…Bit #19.
– In contrast, data types returned to the RTC6 as signed 20-bit values (for example,
actual positions or actual speeds) can be evaluated as a complete signed 32-bit value
returned by get_value (see also code example below).