Specifications

CPU and Input/Output Configuration
6-13
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
6.7 Analog Adjustments
The analog adjustment potentiometers are located under the front access cover of
the module. You can adjust these potentiometers to increase or decrease values
that are stored in bytes of Special Memory (SMB28 and SMB29). These read-only
values can be used by the program for a variety of functions, such as updating the
current value for a timer or a counter, entering or changing the preset values, or
setting limits.
SMB28 holds the digital value that represents the position of analog adjustment 0.
SMB29 holds the digital value that represents the position of analog adjustment 1.
The analog adjustment has a nominal range of 0 to 255 and a repeatability of ± 2
counts.
You use a small screwdriver to make the adjustments: turn the potentiometer
clockwise (to the right) to increase the value, and counterclockwise (to the left) to
decrease the value. Figure 6-10 shows an example program using the analog
adjustment.
STL
LD I0.0
BTI SMB28, VW100
LDN Q0.0
TON T33, VW100
LD T33
= Q0.0
I0.0
B_I
EN
OUTSMB28 IN VW100
Q0.0
TON
IN
VW100 PT
T33
Q0.0T33
Read analog
adjustment 0 and
save the
word-based value in
VW100.
Use the word-based
value as a preset
for a timer. Turn on
Q0.0 when T33
reaches preset.
/
LAD
ENO
Figure 6-10 Example of Analog Adjustment