Bronkhorst Multibus Manual do Utilizador descarregar pdf (Página 9)

BRONKHORST®

Page 9 Operational instructions for digital multibus instruments 9.17.023

2.3 MEASURE AND CONTROL FUNCTIONAL BLOCK DIAGRAM

The main part of a digital instrument is the measuring stage. The base is a highly accurate Analog to Digital converter.

The measuring signal is than processed trough a couple of stages as shown below. In general the path is: ADC scaling,

filtering, linearization (look-up or polynomial), Differentiation (gas flow sensors only), display filtering. In case of a

control system this signal is used to control a valve. The control loop consists of an enhanced PID controller (See the

chapter “Control parameters”).

Digital mass-flow measure / controller functional block diagram

ADC

converter

Bridge potmeter

ADC scaling

Bridge current

Exponential

smoothing

filter

Lookup table

linearization

Polynomial

linearization

Differentiator

filter

(MBC-II only)

Setpoint

Display filter

fmeasure

Measure

PID

controller

VALVE

SENSOR

FLOW

MEASURE

CONTROL

Monitor

Valve Out

MBC3

MBC-II

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Bronkhorst Multibus Manual do Utilizador Página 9