Connecting Pseudo-Differential Voltage Inputs; Connecting Differential Voltage Inputs - Measurement Computing Data Translation DT3034 User Manual

Chapter 4

Connecting Pseudo-Differential Voltage Inputs

Figure 6
panel.
Figure 6: Connecting Pseudo-Differential Voltage Inputs to the DT740

Connecting Differential Voltage Inputs

Figure 7A
panel using differential inputs. (A floating signal source is a voltage source that has no
connection with earth ground.) For floating signal sources, you need to provide a bias return
path by adding resistors R1 to R16 for channels 0 to 15, respectively.
If the input signal is +10 V, then the common-mode voltage could be 1 V. Theoretically, the
resistor value (R
However, when you add noise from external sources to the high impedance, a resistor value
of 100  to 100 k is more practical.
In Figure
to use bias return resistors. R
to balance the bridge. Note that the negative side of the bridge supply must be returned to
analog ground.
46
shows how to connect pseudo-differential voltage inputs to the DT740 screw terminal
Signal Source

+
Vsource
0

+
Vsource
1
*
Remove Jumper W1 to use Amp
Low as a remote ground sense.
V
CM
(Shown for Channels 0 and 1)
illustrates how to connect a floating signal source to the DT740 screw terminal
) should be 1 V divided by the input bias current (20 nA) or 50 m.
b
7B, the signal source itself provides the bias return path; therefore, you do not need
Analog In 0
TB1
TB2
Analog In 1
TB3
Analog Ground
*Make this connection as close to V
possible to reduce ground loop errors.
V is the common-mode voltage for all 32
cm
analog inputs.
is the signal source resistance while R
s
DT740 Panel
TB33
TB34
as
sources
is the resistance required
v