198 Measurement Technique
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
It is not sufficient to connect a differential voltage between +INX and -INX. The operational amplifier
only works correctly if its reference ground (GND) is not floating but is grounded.
A reference ground must be established in the measurement chain. There are various techniques as
well as considerations. In some arrangements, grounding the sensor is preferred, in others grounding
the measurement system (imc CANSAS chassis). Either way, ground loops must be avoided.
Grounding is also recommended as a way of avoiding the buildup of high or dangerous potential
differences between exposed conducting parts (such as the chassis) and ground.
If the sensor does not make Power_Gnd and -Ua separately accessible, then they must be considered
connected at the sensor. In that case that is simply the ground connection.
5.1.3.1.6 Single-signal/ Two-signal
The single signal counter returns a simple pulse sequence. This means that the pulse count and the time
between pulses can be determined, but not the rotation direction of the incremental counter.
A two signal encoder returns two pulse sequences with a 90° offset. Along with the pulse frequency, the
rotation direction can also be indicated as positive or negative. A measurement with two-signal counters
is selected in the combobox "Measurement mode" together with the desired operation type.
5.1.3.1.7 Zero pulse (index)
The zero pulse starts the encoder channels' counter mechanism. This means the measured values are
only recorded if an event occurs at the index-channel. If measurement without a zero pulse is selected,
the measurement starts directly upon activation of the imc CANSAS-INC4.
The system only takes the zero pulse into account following configuration or after starting the INC4
module. Restarting the measurement does not cause a reset.
If the zero pulse fails to appear, the INC4 does not start measurement at all. In that case, the channels
only return zero.
The index channel only applies to all four channels of the module.
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