Installation manual

Frequently Asked Questions
900M050U00  Athena Controls, Inc. 20-3
20.6 Why isn’t the setpoint displayed all the time?
The controller’s dSPLdSPL (display) menu contains a bLAnbLAn (setpoint blanking) parameter that
can be used to specify the number of seconds the setpoint is displayed. Once the
configured time period has elapsed the setpoint display will go blank and remain blank
until any key is pressed. Pressing any key will cause the controller to display the setpoint
again. The setpoint will remain on display until the period specified in the setpoint
blanking parameter has elapsed.
If you want the setpoint to be displayed all the time while the unit is in a control mode,
turn off the blanking function by setting the setpoint blanking parameter to OFF. (See
6.2.2 or 6.3.2.)
20.7 The last digit of the PV display changes very frequently.
How can I slow it down?
If the display is configured to show one or more decimal places, those values might
change frequently, sometimes so quickly that the value is hard to read. Go to the dSPLdSPL
(display) menu and increase the value of the dFILdFIL (display filter) parameter. The display
filter parameter is used to specify the minimum time period between changes of the
displayed PV value. The display filter value has no effect on control. (See 6.2.2 or 6.3.2.)
In contrast, the input menu’s input filter does affect control, because the input filter is
used to specify the time period over which the controller will average the input values
before using the value in the calculation of control output values. (See 5.6.3 or 5.7.4.)
20.8 Why is the setpoint changing? I haven’t touched the
controller!
As described in 1.6, the setpoint used (and displayed) when the controller is operating in
“normal”mode (automatic) is not always entered by the operator as described in 2.4.2.
• The active setpoint can come from a recipe; see 1.6.2.
• The active setpoint can be written to the controller from a host computer; see 1.6.3.
• A second setpoint can be used when an external device triggers an optional switch in
the controller; see 1.6.4.
• The setpoint can come from an external device by means of an optional analog input;
see 1.6.5.
For the algorithm used by the controller to determine which setpoint is the “active”
setpoint, that is, the setpoint being used now, see 1.6.6.