UMAX030211 Version 1.0.2. Preliminary Documentation – May be subject to change
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Each system will have to be tuned for the optimum output response. Response times, overshoots
and other variables will have to be decided by the customer using an appropriate PID tuning strategy.
2.4.
Lookup Table Function Block
The lookup table (LTz) function blocks are not used by default.
Figure 12 – Lookup Table Objects
Lookup tables are used to give an output response of up to 10 slopes per input.
The array size
of the objects 30z5h
LT0z Point Response
, 30z6h
LT0z Point X-Axis PV
and 30z7h
Point Y-Axis
PV
shown in the block diagram above is therefore 11.
Note: If more than 10 slopes are required, a Programmable Logic Block can be used to combine up
to three tables to get 30 slopes, as is described in Section 0.
A parameter that will affect the function block is object
30z5h sub-index 1
which defines the “
X-Axis
Type
”. By default, the tables have a
‘Data Response’
output (0). Alternatively, it can be selected as
a
‘Time Response’
(1).
There are two (or three) other key parameters that will affect how this function block will behave
depending on the “
X-Axis Type
” chosen. If chosen
‘Data Response’
, then the objects 30z0h
Lookup
Table z Input X-Axis Source
and
30z1h
Lookup Table z Input X-Axis Number
together define
the control source for the function block. When it is changed, the table values in object 30z6h need
to be updated with new defaults based on the X-Axis source selected as described in Tables 15 and
16. If however, the “
X-Axis Type
” is chosen to be
‘Time Response’
, an additional parameter is taken
into consideration - object 30z2h,
Lookup Table z Auto Repeat
. These will be described in more
detail in Section 2.4.4.
