TM
Page 23
Reference manual Foundation Fieldbus Control module
DOC.RM.QC34.E Rev: A
October, 2006
4.2.3.2 CFG_SWITCH_POINTS
If the default configuration is not suficient for your
application, the switch points can be configured.
For the QC34 Module, there are three topics con-
cerning the configuration of the switch points.
1 Mechanical limit stops.
Normally the mechanical limit stops limit the stroke
of the actuator. (To adjust the mechanical limit
stops see DOC.IOM.Q.1 chapter 3).
If the mechanical limit stop setting is changed, or
the valve does not reach the fully open or closed
positions (due to wear in the valve), the Open and
Closed end positions have to be re-configured to
assure position feedback.
2 "Open" and "Closed" end positions.
There are two procedures to re-configure the end
positions:
1 If it is safe to cycle the actuator, perform the
initialization procedure (see §3.2).
2 If it is not safe to cycle the actuator, perform the
following re-assignment procedure:
1 Go to Transducer block.
2 In case the "Open" position needs an update:
Set sub parameter OPEN_END_POSITION of
parameter CFG_SWITCH_POINTS to:
"set to current position".
3 In case the "Closed" position needs an update:
Set sub parameter CLOSED_END_POSITION
of parameter CFG_SWITCH_POINTS to:
"set to current position".
3 "Open" and "Closed" stop offset.
The "Open" or "Closed" offset value is the number
of degrees before the end of stroke within which
the switches will be activated or deactivated.
Default values for both positions are (see figure
4.1):
- Default offset 10° before end of stroke.
- Adjustable range 5° to 30° before end of
stroke
Sub parameters OPEN_STOP_OFFSET and
CLOSED_STOP_OFFSET can be used to change
the end stop offsets and can be set per ° (degree)
The FieldQ
™
QC34 Control module will be shipped
with the default feedback characteristic, as per figure
4.1. This feedback characteristic is operational after
initialization (see chapter 3) and is suitable for most
applications.
Default setting
after initialization
Fig. 4.1 Feedback characteristic
10˚max
10˚max
5˚
30˚
30˚
5˚
End
position
End
position
End stop
offsets
Adjustable
range
