# Learn

Navigation: Valve Firmware > Pressure Control > Adaptive algorithm > # Learn |

The Learn adapts the PID controller of the valve to the vacuum system and its operating conditions. A Learn must be executed only once during system setup. The Learn routine determines the characteristic of the vacuum system. Based on this, the PID controller is able to run fast and accurate pressure control cycles.

This characteristic depends on various parameters such as chamber volume, conductance and flow regime. Therefore it must be performed with a specific gas flow according to instruction below.

The result of Learn is a pressure versus valve position data table. This table is used to adapt the PID parameters. The data table is stored in the device memory which is power fail save. The data table can be up-/downloaded via CPA4 Adaptive Learn Data or remote interface. Due to encoding the data may not be interpreted directly.

By an Open, Close, Position or Pressure Control command the routine will be interrupted.

Parameter | Description
Bank Selection | Select one of four learn bank to place the result of the learn procedure. Note: Be sure the pressure controller selects this learn bank!
Pressure Limit [SFS] | Limit pressure to which pressure the learn shall be executed. The value is related to the sensor full scale of high sensor. 1.0 means the whole pressure range of the sensors.
Open Speed | Define the speed for opening the valve during the learn procedure. May be necessary to prevent a pump from crashing. 1.0 means full speed (100%).
Status | State of the current learn 0: Not Started 1: In Progress 2: Completed Successfully 3: Aborted 4: Failed
Warning Info | Warning of current learn procedure: Bit 0: Learn is running Bit 1: Checksum error (learn data corrupt) Bit 2: Learn procedure terminated by user Bit 3: Pressure at position open > 50% of pressure limit Bit 4: Pressure at minimal conductance position < 10 % of pressure limit Bit 5: Pressure falls while move valve in direction of close Bit 6: Pressure at open position does not match pressure of previous open Bit 7: Learn procedure terminated by program Bit 8: Pressure <= 0 at open position (no gas flow set?)