A421 Series Standard Electronic Temperature Controls Installation Instructions
11
Viewing and Changing Values in the Advanced
Menu
To access the Advanced menu and view and change
the parameter values, follow these steps:
Restricting User Adjustment
You can restrict user adjustment of the A421 control to
either just OFF value (control band) only and limit the
range of this value (Figure 9).
You set the A421 control into the restricted adjustment
mode by positioning the jumper located on the circuit
board next to the TB3 terminal block. See
Control to Restricted Adjustment Mode
.
Note:
Setting the A421 control up in the Restricted
Mode prevents casual users from over-adjusting the
control in your application, or from inadvertently
changing the mode of operation from cooling to heating
or heating to cooling (by over-adjusting the
On
value or
OFF
value).
When the A421 control is set up in the restricted
adjustment mode, the following behavior is enforced:
•
The restricted temperature adjustment range is
defined by the selected High Temperature Stop
(
HtS
) and Low Temperature Stop (
LtS
) values.
•
The control band (differential) is defined by the
On
and
OFF
values, and the control band between On
and OFF remains fixed (not adjustable).
•
Only the
OFF
value can be adjusted, the control
band remains fixed, and the On value
automatically shifts equal to the OFF value
adjustment.
•
The
OFF
value can only be adjusted to values that
maintain the entire control band within the
restricted temperature adjustment range defined
by HtS and LtS. See Figure 9.
•
The basic and advanced menus are not available.
Only the restricted adjustment mode menu is
available and only the
OFF
value can be adjusted.
See Figure 11.
Setting the Control to Restricted Adjustment Mode
To set up the restricted adjustment feature:
1.
Ensure that the A421 is not in the restricted mode
(the jumper is positioned on both pins). See
Figure 10.
2.
Select the
OFF
and
On
values that define the
application’s required control band (Figure 9).
3.
Change the
HtS
and
LtS
temperature
values to
define the restricted adjustment range (Figure 9).
1.
With the Main screen displayed,
press and hold
and
simultaneously for 5 seconds. The
LCD displays
Un
, which is the first
parameter code screen displayed in
the Advanced menu.
2.
Press
or
to scroll through all of
the Advanced parameter codes and
display the preferred code.
3.
With the preferred parameter code
displayed, press
MENU
to display the
current parameter value for the code.
4.
With the current parameter value
displayed, press
or
to scroll
through all of the parameter code’s
usable values and display the
preferred value.
5.
With the preferred parameter value
displayed, press
MENU
to save the
displayed value and go to the next
parameter code.
38
o
F
Un
HtS
212
o
F
75
o
F
Figure 9: Adjustment Behavior in
Restricted Adjustment Mode
