Common Mode - Intab PC-logger 3150 How To Use Manual

N.B.
In all work connecting signals to the logger you have to take the following
points into account :
• Analog ground is common to all channels.
• Analog ground is internally connected to RS-232 signal return (D-sub
pin 7).
• Analog ground is internally connected to power input return ( pin 2).
• Analog ground is internally connected to trig input and output signal
return ("G")
• Analog ground is internally connected to negative V-out.
3.3.2

Common Mode

To maintain accuracy in your measurements you have to take the common
mode range into account. The common mode range is 10V.
This is another way of looking at or taking advantage of the "differentiality" of
the inputs.
The impedances between "Gnd" and positive and "Gnd" and negative inputs
are very high. This means that unless they in some way are connected, the
inputs may float electrically, way beyond the allowed limit.
The inputs will not be damaged by voltages above this as long as they are
within 30V off signal ground.
The following sections of this manual will provide some examples of how
transducers can be connected.
12
INTAB Interface-Teknik AB