416 Properties of the Modules
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
6.20.3 Current measurement
6.20.3.1 Differential current measurement
For current measurement could be used the DSUB plug ACC/
DSUB-I2. That connector comes with a 50 shunt and is not
included with the standard package. It is also possible to
measure a voltage via an externally connected shunt.
Appropriate scaling must be set in the user interface. The value
50 is just a suggestion. The resistor needs an adequate level
of precision. Pay attention to the shunt's power consumption.
The maximum common mode voltage must be in the range
±10 V for this circuit, too. This can generally only be ensured if
the current source itself already is referenced to ground. If the
current source is ungrounded a danger exists of exceeding the
maximum allowed overvoltage for the amplifier. The current
source may need to be referenced to the ground, for example
by being grounded.
The sensor can also be supplied with a software-specified voltage via Pins +VB(C) and -VB(D).
Since this procedure is a voltage measurement at the shunt resistor, voltage measurement must also
be set in the imc DEVICES interface.
The scaling factor is entered as 1/R and the unit as A (0.02 A/V = 1/50 ).
6.20.3.2 Ground-referenced current measurement
In this circuit, the current to be measured flows through the
120 shunt in the amplifier. Note that here, the terminal -
VB(D) is simultaneously the device's ground. Thus, the
measurement carried out is single-end or ground referenced.
The potential of the current source itself may be brought into
line with that of the units ground. In that case, be sure that
the device unit itself is grounded.
In the settings interface, set the measurement mode to
Current.
Note that the jumper between +IN(A) and +I; ¼Bridge(G)
should be connected right inside the connector.
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