usb-6008 bias resistors?

[Heyla]

Table 6 of the USB-6008 "User Guide & Specifications" describes the GND terminal as necessary for bias return currents in differential mode, but Figure 8 doesn't reference the connection and I find no other description of potential referenced/floating signal issues.  Are bias resistors needed for ungrounded differential signals, or am I misunderstanding the Table 6 description?  If needed, is there a stated ohm value like that suggested for use on the 9205 (10k-100k)?

Thanks

[Jim_S]

Hello,

After looking over the 6008 manual, it isn't needed to have the bias resistors when taking a differential measurement. If you noticed that you aren't reading the correct measurements for your device, I would try to place the bias resistor in and see if this fixes the issue. As for the value of the bias resistors, you would want to choose a resistor between 10k-100k as can be seen in the Field Wiring and Noise Considerations for Analog Signals.