Process Value Settings; Process Value Limits; Process Value Scaling - Siemens SIMATIC S7-1200 Function Manual

6.2.2

Process value settings

6.2.2.1

Process value limits

You must specify an appropriate absolute high limit and low limit for the process value as
limit values for your controlled system. As soon as the process value violates these limits, an
error occurs (ErrorBits = 0001h). Tuning is canceled when the process value limits are
violated. You can specify how PID_Temp responds to errors in automatic mode in the output
settings.
6.2.2.2

Process value scaling

If you have configured the use of Input_PER in the basic settings, you will need to convert
the value of the analog input into the physical quantity of the process value. The current
configuration is displayed in the Input_PER display.
Input_PER is scaled using a low and high value pair if the process value is directly
proportional to the value of the analog input.
Procedure
To scale the process value, follow these steps:
1. Enter the low pair of values in the "Scaled low process value" and "Low" input fields.
2. Enter the high pair of values in the "Scaled high process value" and "High" input fields.
Default settings for the value pairs are saved in the hardware configuration. Proceed as
follows to use the value pairs from the hardware configuration:
1. Select the instruction PID_Temp in the programming editor.
2. Interconnect Input_PER with an analog input in the basic settings.
3. Click on the "Automatic setting" button in the process value settings.
The existing values are overwritten with the values from the hardware configuration.
PID control
Function Manual, 03/2017, A5E35300227-AC
Using PID_Temp
6.2 Configuring PID_Temp
163