User Manual V 1-4.XX User guide

Using the Function Block 10-13
Figure 10.15
Maximum/Minimum Function Block
In1 is compared to In2. The value passed to Function Output 1
(parameter 213) depends on In3.
As an example, you could use the maximum/minimum function block
to make sure that the speed in a mixing process does not exceed a
specified limit. Figure 10.16 shows this application.
Figure 10.16
Example of a Mixing Process
For this example, the PLC is used to monitor the mixing process. The
user can control the speed of the mixing process, up to the maximum
speed specified by the PLC. The maximum/minimum function block
is used to select whichever value is smaller (the minimum): the speed
specified by the PLC or the speed specified by the pot.
To set up the function block for this application, you would need to
enter the values shown in Figure 10.17.
200
Func 1 Eval Sel
0 – 17
198
Function In1
199
Func 1 Mask/Val
I
V
Maximum/Minimum
Function Block
203
Func 2 Eval Sel
0 – 17
201
Function In2
202
Func 2 Mask/Val
I
V
212
Function Sel
10 In1, In2 > [max] Out1
In1, In2 < [min] Out1
In3: If: Then:
False min —> Out1
True max —> Out1
In1
In2
213
Function Output 1
206
Func 3 Eval Sel
0 – 17
204
Function In3
205
Func 3 Mask/Val
I
V
In3
Out1
If In3 is: Then this value is passed to Function Output 1:
False The smaller value
True The larger value
PLC
User Speed
Smaller Value
Maximum Speed
.
.
.
User±Controlled Pot
Minimum/Maximum
Function Block
This function block is
set up to select the
minimum of two values.