Example: Configuration of the actual value and setting value for the air pressure controller

The air pressure controller controls the differential pressure and compensates for temperature and pressure fluctuations in the engine room/boiler house.

The control variable is the differential pressure that is imported in the control system via a differential pressure transmitter. As an input signal ("Actual value combustion air pressure" = channel 313), this differential pressure is connected to the analog input module (address: Node-ID = 50 and Value-ID = 1).

Based on the transmitted differential pressure, the controller sets the speed for the combustion air fan. The required analog output signal ("output (y) combustion air pressure controller" = channel 169) is connected to the analog output module (address: Node-ID = 50 and Value-ID = 3).

The following signals are therefore required:

1. Analog input signal (channel 313): "Actual value of combustion air pressure"

   Differential pressure (x = actual value), which is measured in front of the combustion air damper relative to the furnace.

   0 - 60 mbar ≙ 4 - 20 mA

2. Analog output signal (channel 169): "Output (y) of combustion air pressure controller"

   Speed (y = setting value) for the combustion air fan

   0 - 100 % ≙ 4 - 20 mA

The figure below illustrates this example:

The analog channels required for this example must be configured as follows:

Analog input channel 313

Analog input channel 169