Operating Manual CMGZ432
5
4 System description
fig. 1: Basic structure of a drive control system on an unwinding application
C432001e
4.1 Functional description
The force sensors measure the tension force in the material and transmit the measuring
value as a mV signal to the electronic unit CMGZ432. The electronic unit amplifies the
mV signal and calculates the error to the reference value. If the material tension is too
low, the drive will be driven slower; if the material tension is too high, the drive will be
driven faster.
4.2 Force sensors
The force sensors are based on the flexion beam principle. The flexion is measured by
strain gauges and transmitted to the electronic unit as mV signal. Due to the wheatstone
wiring of the strain gauges, the measured value is according also to the power supply. So,
the force sensors are supplied from the CMGZ432 by a very accurate power supply.
4.3 Electronic unit CMGZ432
Common
The electronic unit contains a microprocessor to handle all calculations and
communications, the highly accurate sensor power supply and the signal amplifier for the
measuring value. As operation interface it provides 4 keys, 4 LED’s and a 2x16
characters display in the front of the electronic unit. All inputs are saved in an EEPROM.
The electronic unit has no jumpers or trimmers to keep most accurate long-time and
temperature stability.
There can be connected one or two force sensors to the electronic unit.
Strain gauge amplifier
The strain gauge amplifier provides the highly accurate 4V power supply. A highly
accurate, fixed difference amplifier rises the mV signal up to 10V. This signal will be fed
to the A/D converter. The microprocessor then does all application-specific calculations
with the digitized measuring value (such as offset, gain, low-pass filter).
