Measurement Computing PCI-DAS6023 - Manual (Page 11)

PCI-DAS6023 and PCI-DAS6025 User's Guide Installing the PCI-DAS6023 or PCI-DAS6025
11
Configuring the hardware
All of the hardware configuration options on the PCI-DAS6025/6023 are software controlled. You may select
some of the configuration options using InstaCal, such as the analog input configuration (16 single-ended or
eight differential channels), the edge used for triggering when using an external pacer and the source for the two
independent counters. Once selected, any program that uses the Universal Library will use these selections to
initialize the hardware according to these selections.
Following is an overview of the available hardware configuration options for the PCI-DAS6023 and PCI-
DAS6025 boards. For general information regarding signal connection and configuration, refer to the Guide to
Signal Connections. This document is available on our web site at www.mccdaq.com/signals/signals.pdf .
Differential input mode
When all channels are configured for differential input mode, eight analog input channels are available. In this
mode, the input signal is measured with respect to the low input. The input signal is delivered through three
wires:

The wire carrying the signal to be measured connects to CH# IN HI.
 The wire carrying the reference signal connects to CH# IN LO.
 The third wire is connected to LLGND.
Differential input mode is the preferred configuration for applications in noisy environments or when the signal
source is referenced to a potential other than PC ground.
Single-ended input mode
When all channels are configured for single-ended input mode, 16 analog input channels are available. In this
mode, the input signal is referenced to the board’s signal ground (LLGND). The input signal is delivered
through two wires:

The wire carrying the signal to be measured connects to CH# IN HI.
 The second wire is connected to LLGND.
Non-referenced single-ended input mode
This mode is a compromise between differential and single-ended modes. It offers some of the advantages of
each mode. Using non-referenced single-ended mode, you can still get noise rejection but not the limitation in
the number of channels resulting from a fully differential configuration. The possible downside is that the
external reference input must be the same for every channel. It is equivalent to configuring the inputs for
differential mode and then tying all of the low inputs together and using that node as the reference input.
When configured for non-referenced single-ended input mode, 16 analog input channels are available. In this
mode, each input signal is not referenced to the board’s ground, but to a common reference signal (AISENSE).
The input signal is delivered through three wires:

The wire carrying the signal to be measured connects to CH# IN HI.
 The wire carrying the reference signal connects to AISENSE.
 The third wire is connected to LLGND.
This mode is useful when the application calls for differential input mode but the limitation on channel count
prevents it.