Operation Manual EMGZ490A
30.08.2019
13
4.5
Limit Violations
The amplifier checks the analogue input and output on limit violations. It checks
whether the force sensor is mechanically overloaded (overload test). At the output, it is
checked whether the voltage output over or under shoots the physically possible value
in relation to the amplified input.
A ) Overload Test
The overload test is performed with the raw data received from A/D-converter. It is
therefore not related to a particular force and can be used regardless of the installed
system.
Test Rules:
The FMS force sensors deliver at the rated nominal force at the output 9mV.
The maximum load at the mechanical hard stop is 12.4mV. The amplifier checks the
overload in the positive measuring direction (red point) as well as in the negative
direction. The limits are therefore 12mV respectively. -12mV. Upon reaching one of
these limits, the Status Bit is set to Overload. The status Bit is reset, if the measured
value falls 0.5 mV below the limits.
B ) Overflow/Underflow Test
Over- or underflow are determined by using the output (calculated with the gain factor).
If the output exceeds the maximal possible value, there is an overflow. If it drops below
the minimal value, there is an underflow.
Test Rules:
The output voltage varies between 0 and +10 V. For the test a hysteresis of ±10 digits is
applied, in order to prevent error bits to respond at any small overflow or underflow. The
overflow is thus triggered at the output reaching the theoretically calculated value
10.05V. For the underflow applies value of -0.05V. Upon reaching one of these limits,
the corresponding Status Bits are set. The Status Bits are re-set as soon as the output
enters the range 0.05V and 9.95V.
