UMAX090600 Version 1
Preliminary Documentation – May be Subject to Change
11-48
1.5.1.
X-Axis, Input Data Response
In the case where the
X-Axis Type
=
‘Data Response’,
the points on the X-Axis represents the data
of the control source.
For example, if the control source is a Thermistor input with an operating range of 20Ohm to
2.5kOhm, the X-Axis will be setup to have a default
Point 1 – X Value
of 0.2kOhm, and setpoint
Point
10 – X Value
will be set to 2.5kOhm. The
Point 0 – X Value
will be set to the default value of 0.0kOhm.
For most Data Responses, the default value at point (0,0) is [0,0].
However, should the minimum input be less than zero, for example if a CAN message is used as the
source that is reflecting temperature in the range of -40ºC to 210ºC, then the
Point 0 – X Value
will
be set to the minimum instead, in this case -40ºC.
The constraint on the X-Axis data is that the next index value is greater than or equal to the one
below it, as shown in the equation below. Therefore, when adjusting the X-Axis data, it is
recommended that X
10
is changed first, then lower indexes in descending order.
MinInputRange <= X
0
<= X
1
<= X
2
<= X
3
<= X
4
<= X
5
<= X
6
<= X
7
<= X
8
<= X
9
<= X
10
<= MaxInputRange
As stated earlier, MinInputRange and MaxInputRange will be determined by the X-Axis Source that
has been selected.
If some of the data points are
‘Ignored’
as described in Section 1.5.4, they will not be used in the X-
Axis calculation shown above. For example, if points X
4
and higher are ignored, the formula becomes
MinInputRange <= X
0
<= X
1
<= X
2
<= X
3
<= MaxInputRange instead.
1.5.2.
Y-Axis, Lookup Table Output
The Y-Axis has no constraints on the data that it represents. This means that inverse, or
increasing/decreasing or other responses can be easily established.
For example, should the X-Axis of a table be a resistive value, the output of the table could be
temperature from an NTC sensor in the range Y
0
=125ºC to Y
10
= -20ºC. If this table is used as the
control source for another function block (i.e. transmitted over CAN), then Xmin would be -20 and
Xmax would be 125 when used the linear formula.
In all cases, the controller looks at the
entire range
of the data in the Y-Axis setpoints and selects
the lowest value as the MinOutRange and the highest value as the MaxOutRange. They are passed
directly to other function blocks as the limits on the Lookup Table output. (i.e used as Xmin and
Xmax values in linear calculations.)
However, if some of the data points are
‘Ignored’
as described in Section 1.5.4, they will not be used
in the Y-Axis range determination. Only the Y-Axis values shown on EA will be considered when
establishing the limits of the table when it is used to drive another function block, such as an Output
Drive.
