Dewetron DAQP-CFB2, Technical Reference Manual, Page: 14 / 22

14
DAQP-CFB2
DAQP-CFB2 Step Response
The 7th order Butterworth fi ler has an overshoot of 14 % in time domain. Bessel fi lters do not have any
overshoot.
Synchronizing multiple amplifiers
The high amplifi cation of strain gage amplifi ers requires to synchronize the excitation voltage if multiple
channels are used. This is done with pin 8 of the back plane connector. When mixing DAQP-CFB and
DAQP-CFB2 modules please consider that the DAQP-CFB amplifi er only support 5 kHz excitation.
The DAQP-CFB2 off ers three synchronisation modes:
Single: DAQP-CFB2 uses the internal crystal oscillator and outputs no synch signal.
Master: DAQP-CFB2 uses the internal crystal oscillator and serves a synch signal.
Slave: DAQP-CFB2 synchronises the excitation voltage to the synchronisation signal. No sync
amplifi er is required anymore when DAQP-CFB2 is used in slave mode. When switching into
slave mode the frequency is auto detected and cannot be changed anymore.
Sync of up to 16 channels:
Synchronisation of the carrier frequency is required when:
Sensor cables of diff erent CFBs are nearby
Sensors are mounted on the same metal structure (capacitive signal coupling)
No synchronisation is required when:
Isolated sensors are on non-conductive structures
For ranges above 100 mV/V because of the low amplifi cation and therefore less infl uence of crosstalk
between wires and cables.
In some special DEWETRON Racks pin 8 is already in use for customized sensor supply voltage level. If
so, only single mode operation is possible.
Master
Slave Slave Slave Slave
Pin 8
. . .
Module 4 Module 3 Module 2 Module 1 Module 0 Module 15