VDSP-431 system & functional block diagrams
(this page is under construction. 2-14-2002)
The VDSP431 Digital Servo Controller is a set of two different type of modules that when connected together provide a complete intelligent system able to control up to 6 channels of double load cell . Up to (4) sets of VDSP-431 can be combined with (12) VDSP-SCM module to make a a 24 channel, DUAL feedback (AC & DC) digital servo control systems as pictured above in photo 1.
This module is an intelligent DSP base VME module . It can support up to 3 VDSP_SCM
module. The primary features of the VDSP431M are as follows:
A/C Singnal conditioning:
The A/C module is designed around the AD698 LVDT signal conditioner from Analog Devices. The excitation frequency can be set between 20 Hz and 20 KHz by changing capacitors. The VDSP431 AC Module is preset to 10 KHz at the factory. The output of the LVDT demodulator is amplified by the same circuitry utilized by the DC Module. Programmable relays allow the LVDT demodulator to be bypassed. This is so the AC Module can be used to support DC high-level inputs such as a DCDT. The AC excitation can be disabled when DC high-level mode is used. Two fourth order filters, with a cut-off frequency of 500 HZ, remove any residual carrier signal from the demodulator output. The LVDT modules excitation is preset at the factory to 7.0 Vpp at 10.0 KHZ. The demodulator gain is set to output +/- 9 Vdc over full stroke of the LVDT.
D/C Signal conditioning:
Incoming low level LoadCell signals are amplified by high precision low noise, low offset, high impedance instrumentation amplifier. The SCM PGA Modules utilize a two stage instrumentation amplifier design that is able to provide any gain between 1 and 5000.
The Valve driver module is able to drive up to 100 ma into a 200 ohm load. The output of a 16-bit D/A converter drives two power amplifiers that convert the input voltage signal to a current signal. Output of the current is directly proportional to the input signal. The current range is programmable by software using relays.
Four ranges are available :
Load Cell configuration:
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