VAT 615 Series Installation, Operating, & Maintenance Instructions page 35

3.6.7.1 Adaptive algorithm
1. Perform LEARN
LEARN adapts the PID controller of the valve to the vacuum system and its operating conditions. The DeviceNet
learn is "calibration service". 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 'Control
Performance Analyzer' software or remote interface. Due to encoding the data may not be interpreted directly.
By an OPEN VALVE, CLOSE VALVE, POSITION CONTROL or PRESSURE CONTROL command the routine will be
interrupted.
Local operation:
('Control View' resp. 'Control Performance Analyzer')
Go to 'Learn / LEARN' menu and follow instructions.
Note: Gasflow calculation according to
recommendation below is done automatically based
on inputs.
Note: Sensor signal must not shift during LEARN. Wait until sensor signal is stable before LEARN is performed.
Note: Learn may take several minutes. Do not interrupt the routine as a single full run is required to ensure fast and
accurate pressure control. The PID controller covers 5% to 5000% of the gas flow which was used for learn.
Note: To optimize adaptive algorithm of the pressure controller refer to chapter «Tuning of pressure control performance».
VAT Vakuumventile AG, CH-9469 Haag, Switzerland
Tel +41 81 771 61 61 Fax +41 81 771 48 30 CH@vatvalve.com www.vatvalve.com
Installation, Operating & Maintenance Instructions
Series 615 DN 40 (I.D. 1½"), DeviceNet
Remote operation:
(Refer to chapter «Selection Object» resp. «S-Singel
Stage Controller Object» for details)
1. Send EXECUTING
(if not yet selected)
2. Select SETPOINT TYPE
= position control
3. Select CONTROL MODE for position
= open valve
4. Set specific gas flow according to calculation
below and wait until flow is stable.
Autolearn does not need to be performed with the
process gas. Instead N
5. Set LEARN PRESSURE LIMIT to p
(max. pressure to control during process)
6. Send LEARN
®
term for
or Ar may be used.
2
max
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