IMC CANSAS - Input;Output Stage

66 Operation
imc CANSAS Users Manual - Doc. Version 1.9 - 05.12.2014© 2014 imc Meßsysteme GmbH
3.2.4.5 Input/Output stage
This dialog shows the common properties of the input or output channels. The settings and information
this filecard presents depends on the type of module involved.
CANSAS ISO8 Differential amplifier Properties dialog
The dialog elements for each module type are explained in Chapter 4. Here we refer to the C12 module
type as an example.
In the case of a imc CANSAS C12 module, the presence of 12 input channels is indicated. These are
organized into two groups of 6, and the six-packs are configured en bloc. All the inputs are DCcoupled,
non-isolated differential channels.
The imc CANSAS C12 module implements time offset correction for the input channels. The check box
shown on this dialog lets you activate this option.
imc CANSAS C12 Module has two multiplexers for the input channels. This hardware only permits
sequential sampling of the input channels, which means that the channels' data have a time discrepancy.
This offset is corrected by the software, so that the measured waveforms are practically synchronized.
Independently of how many input channels are active, the 12th channel is the control for the offset
correction. Interpolation is used to determine the signal value a channel had when the 12th channel's
value was recorded.
Note
The time offset correction should only be used if the signals are sufficiently band-limited to
apply the Sampling Theorem. Otherwise, significant errors can result due to aliasing effects.
The imc CANSAS hardware allows only sequential sampling of the data acquisition channels
(only one multiplexer is provided). Thus, the channels' sampling times are mutually offset,
although they all take the same starting time. This offset is compensated for by the software if
the option "Time offset correction" is active. Without correction, the time offset is in any case
less than the sampling rate set.
When a rectangular signal is sampled, the FIR-filter causes the signal to appear overshot. You
can check whether the effect is real by switching off the time offset correction.