Measurement Computing PCI-DAS6071 - Manual (Page 9)

PCI-DAS6071 User's Guide Installing the PCI-DAS6071
9
Differential input mode
When all channels are configured for differential input mode, 32 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, 64 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 other 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, 64 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 measure 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.
DAQ-Sync configuration
You can interconnect multiple boards in the PCI-DAS6000 series to synchronize data acquisition or data output.
To do this, order and install a CDS-14-x cable at the DAQ-Sync connectors (P2) between the boards to be
synchronized.
The "x" in the CDS-14-x part number specifies the number of connectors available on the cable, and therefore,
the number of boards you can interconnect. Using a CDS-14-2, you can connect two PCI-DAS6000 series
boards together for I/O synchronization. Using a CDS-14-3, you can synchronize three boards, and so on. You
can connect up to five PCI-DAS6000 series boards. A CDS-14-3 cable is shown in Figure 3 on page 14.
By default, all DAQ-Sync connectors are configured as inputs (slave mode). In order to be useful, one board
must be set through software to serve as the master, and the signal sources of the slave boards must be defined.
D/A external reference
This product is equivalent in the specification and performance to the National Instruments
™
(NI) PCI-6071E.
The Analog Output External Reference Bandwidth is specified at 1 MHz. This signal path is indeed 1 MHz;
however the performance of the D/A converter itself in multiplying mode varies with frequency and code. To
the best of our knowledge, this behavior is not fully explained in documentation presently available from NI.
If you are using the external reference feature of the analog outputs, please refer to the data sheet for the Analog
Devices AD7945. This document summarizes the performance of the D/A converter in multiplying mode.