Measurement Computing CIO-DAS16 - Manual (Page 17)

change your system grounding configuration or add isolation signal conditioning. (Please look at our ISO-RACK and
ISO-5B-series products to add electrical isolation, or give our technical support group a call to discuss other options).
NOTE
Relying on the earth prong of a 120VAC for signal ground connections is not advised.. Different ground
plugs may have large and potentially even dangerous voltage differentials. Remember that the ground
pins on 120VAC outlets on different sides of the room may only be connected in the basement. This
leaves the possibility that the “ground” pins may have a significant voltage differential (especially if the
two 120 VAC outlets happen to be on different phases!)
CIO-DAS16/F and Signal Source Having Isolated Grounds
Some signal sources will already be electrically isolated from the CIO-DAS16/F. The diagram below shows a typical
isolated ground system. These signal sources are often battery powered, or are fairly expensive pieces of equipment
(since isolation is not an inexpensive proposition), isolated ground systems provide excellent performance, but require
some extra effort during connections to assure optimum performance is obtained. Please refer to the following sections
for further details
3.3 WIRING CONFIGURATIONS
Combining all the grounding and input type possibilities provides us with the following potential connection
configurations. The combinations along with our recommendations on usage are shown in Table 3-1 below.
Table 3-1. Input Type Recommendations
Recommended Differential Inputs
Already Isolated
Grounds
Acceptable Single-ended Inputs Already Isolated Grounds
Unacceptable without
adding Isolation
Differential Inputs
Common Mode
Voltage > +/-10V
Unacceptable without
adding Isolation
Single-Ended Inputs
Common Mode
Voltage > +/- 10V
Recommended Differential Inputs
Common Mode
Voltage < +/-10V
Not Recommended Single-Ended Inputs
Common Mode
Voltage < +/-10V
Acceptable Differential Inputs Common Ground
Recommended Single-Ended Inputs Common Ground
OUR VIEW
INPUT
CONFIGURATION
GROUND
CATEGORY
The following sections depicts recommended input wiring schemes for each of the eight possible input
configuration/grounding combinations.
13