Siemens LOGO! Series - Page 221

LOGO! functions
4.4 Special functions list - SF
LOGO!
Manual, 04/2011, A5E03556174-01
221
Setting the Par parameter
The gain and offset parameters are used to adapt the sensors to the relevant application.
View in programming mode:
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Example
In a heating control system, the supply T
v
and return line temperatures T
r
are to be
compared, for example with a sensor at AI2.
A control signal is to be triggered (for example "heater On") when the difference between the
supply and return line temperatures is greater than 15 °C. The control signal is reset when
the difference is less than 5 °C.
The process variable of the temperature is to be shown in parameter assignment mode.
The thermocouples available have the following technical data: -30 to +70 °C, 0 to 10 VDC.
Application Internal mapping
-30 to +70 °C = 0 to 10 V DC 0 to 1000
0 °C 300
→ Offset = -30
Range of values:
-30 to +70 °C = 100
1000
→ Gain = 100/1000 = 0.1
On threshold = 15 °C Threshold = 15
Off threshold = 5 °C Threshold = 5
See also topic "Calculating the gain and offset of analog values (Page 154) ".