Eurotherm 584SV Series, Product Manual

Page: 80 / 255

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The following rules apply when programming:
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•
Function block output parameter values cannot be changed (because they are a result of the
function block’s processing)
•
Function block input parameter values that receive their values from a link cannot be
changed (as they will change back to the value they receive from the link when the Inverter
is running).
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•
A link’s destination tag must be set to an
input parameter (only one link per input
parameter).
•
A link’s source tag may be set to any
parameter. Both input and output
parameters can be used as a source.
•
Disable a link by setting the “destination”
and “source” tag to zero.
•
Setting a link’s source tag to a negative
value (i.e. 18 becomes -18) nominates it as
a feedback link, forcing this link to be
executed first. This is used to reduce
execution timing delays in a feedback loop
situation.
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The complete block diagram is executed every 20ms, with individual control blocks executing
within 2ms. Just before a function block is executed, all the links that have that block as their
destination are executed, thereby copying new values in to the block’s parameter inputs. The
input parameters are then processed to produce a new set of output parameters. The execution
order of the blocks is automatically arranged for minimal delay.
•
The output value transferred by a link on execution is clamped to be between the maximum
and minimum value for its destination input parameter.
•
If a links’ source and destination parameters have different decimal point positions, there is
no automatic adjustment. Use a VALUE FUNCTION function block to modify the input
into the correct destination format. Refer to the table below for the result of linking different
parameters types.
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+ WKH # UHVXOW , + WKH # UHVXOW ,
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433133 ;;; 1 ;; ;;;; 1 ; 433313
433133 ;;; 1 ;; ; 1 ;;;; 413333
758( %RROHDQ ;;; 1 ;; 3134
)$/6( %RROHDQ ;;; 1 ;; 3133
3134 ;;; 1 ;; %RROHDQ 758(
3133 ;;; 1 ;; %RROHDQ )$/6(
/2&$/ # 21/< #+4, (QXPHUDWHG ;;; 1 ;; 3134
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Table 6-1 Execution Rules
Feedback Link
18
BLOCK
BLOCK
BLOCK
[99]
-18
Figure 6-1 Quick Link Information:
-18 .. (-)
→ →→ →
[99]