Continuous Temperature Controller Fb 58 "Tcont_Cp - Siemens SIMATIC Manual

Continuous Temperature Controller FB 58 "TCONT_CP"

Process Value Format Conversion CRP_IN (PER_MODE)
The CRP_IN function converts the peripheral value PV_PER to a floating-point
format depending on the switch PER_MODE according to the following rules:
PER_MODE
0
1
2
Process Value Normalization PV_NORM (PF_FAC, PV_OFFS)
The PV_NORM function calculates the output of CRP_IN according to the following
rule:
"Output of PV_NORM" = "Output of CPR_IN" * PV_FAC + PV_OFFS
It can be used for the following purposes:
•
Process value correction with PV_FAC as the process value factor and
PV_OFFS as the process value offset.
•
Normalization of temperature to percentage
You want to enter the setpoint as a percentage and must now convert the
measured temperature value to a percentage.
•
Normalization of percentage to temperature
You want to enter the setpoint in the physical temperature unit and must now
convert the measured voltage/current value to a temperature.
Calculation of the parameters:
•
PV_FAC = range of PV_NORM/range of CRP_IN;
•
PV_OFFS = LL(PV_NORM) - PV_FAC * LL(CRP_IN);
where LL is the lower limit
With the default values (PV_FAC = 1.0 and PV_OFFS = 0.0), normalization is
disabled. The effective process value is output at the PV output.
Note
With pulse control, the process value must be transferred to the block in the fast
pulse call (reason: mean value filtering). Otherwise, the control quality can
deteriorate.
2-2
Output of Analog Input Type
CRP_IN
PV_PER * 0.1 Thermoelements; PT100/NI100; standard
PV_PER * 0.01 PT100/NI100; climate;
PV_PER * Voltage/current
100/27648
Unit
°C; °F
°C; °F
%
PID Temperature Control
A5E00125039-02