S5-95F
Analog Value Processing
11.6 Analog Value Conversion: Function Blocks FB250 and FB251
11.6.1 Reading in and Scaling an Analog Value
- FB250 -
Function block FB250 reads in an analog value from an analog input module and outputs a value XA
in the scale range specified by the user.
Specify the type of analog value representation for the module (channel type) in the KNKT
parameter.
Define the desired range using the "upper limit" (OGR) and "lower limit" (UGR) parameters.
Table 11-8. Call and Parameter Assignments of FB250
Parameter
Explanation
Type
BG
Slot number
D KF
KNKT
Channel number
Channel type
D KY
0 to 7
KY = x,y
x = 0 to 3
y = 3 to 6
3: Absolute value
representation
(4 to 20 mA)
4: Unipolar represen-
tation
5: Bipolar absolute value
6: Bipolar fixed-point
number
OGR
Upper limit of the output
value
D KF
UGR
Lower limit of the output
value
D KF
EINZ
XA
Output value
Q W
FB
Error bit
Q BI
BU
Range violation
Q BI
-32767 to +32767
-32767 to +32767
Not relevant
Scaled analog value is “0”
on wirebreak
“1” on wirebreak, illegal
channel or slot number or
illegal channel type
“1” when nominal range is
exceeded
Assignment
: JU FB 250
NAME : RLG:AI
BG :
KNKT :
OGR :
UGR :
EINZ :
XA :
FB :
BU :
STL
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a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
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Figure 11-7. Scaling Schematic for FB250
UGR
Representation of
the analog input
module
User scaled range
OGR
Scaled range
Scaling Schematic
EWA 4NEB 812 6210-02
11-11