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Q10053 Accessing analog I/O extensions in customized xDAP 7400

Tags: Help, xDAP, analog input, backplane, slots, channels, connectors, addressing

Applies to: xDAP 7400, DAPL 3000 1.00, MSXB037-05-E2E08-B

I have a factory-customized xDAP 7400 using analog expansion boards to provide BNC-style connectors. How do I access signals connected to these boards?

Certain factory-customized xDAP 7400 configurations use analog expansion boards to provide connector or filtering alternative to the standard xDAP 7400 configuration. If you have a customized system, you will need to use special addressing notations to access the signals connected to the added boards.

The extra boards connect to the xDAP through backplane connections compatible with a-Series analog backplane cards. The boards most typically used are MSXB037-05-E2E08-B analog expansion, as these provide BNC connector alternatives to standard high-density D input connector. Labeling the front panel slots of the xDAP 7400 enclosure from left to right as J1, J2, ..., J7, then the two slots at positions J4 and J5 are the ones with the compatible analog backplane connections.

To access signals connected at panels in these two slot positions, you must tell the DAPL system how the signals are routed. DAPL 3000 version 1.00 introduces some new signal routing identifiers for this purpose. For an xDAP 7400, the routing names are:

  • c0; this sends signals to the standard D-connector, and it is the default connection if no signal routing is specified.
  • c1; this sends signals to the first a-Series analog backplane slot at panel location J4.
  • c2; this sends signals to the second a-Series analog backplane slot at panel location J5.

The routing identifiers can then be added as a prefix to the usual pin designation notation in the set commands that you use to define your input sampling configurations. The individual pins for the analog board connectors are differential inputs. The xDAP 7400 supports 8 differential inputs, corresponding to the 8 hardware channel selectors of the xDAP 7400. The individual channels are addressed for each board using the familiar differential input channel notations d0 through d7. For example, to address one differential channel d2 routing the signal through connection c1 to the board in slot location J4, your input configuration would specify:

    set  ipipe0  c1:d2 

The analog backplane slots at connector locations J4 and J5 are wired independently of one another, allowing for 16 distinct differential analog input pairs on the backplane. Since the xDAP 7400 provides 8 independent channel selectors and 8 parallel digitizers, when you are using both slots you will most likely want to configure the system to sample 8 inputs from each slot on alternating sampling cycles, as in the following example.

    set ipipe0  c1:d0    // Analog connector at slot J4
    set ipipe1  c1:d1    // Access all 8 channels, d0 to d7
    set ipipe2  c1:d2 
    set ipipe3  c1:d3 
    set ipipe4  c1:d4 
    set ipipe5  c1:d5 
    set ipipe6  c1:d6 
    set ipipe7  c1:d7

    set ipipe8  c2:d0    // Analog connectors at slot J5
    set ipipe9  c2:d1    // Access all 8 channels, d0 to d7
    set ipipe10 c2:d2 
    set ipipe11 c2:d3 
    set ipipe12 c2:d4 
    set ipipe13 c2:d5 
    set ipipe14 c2:d6 
    set ipipe15 c2:d7

In general, the a-Series analog input slots on xDAP 7400 are compatible with a-Series accessory boards that do not require input expansion addressing, and have the property that they can drive the analog backplane differentially (so that signals reach the DAP through a pair of signal lines). Not all of the a-Series boards have these properties. Some a-Series accessory boards that are compatible with xDAP 7400 and likely to be useful include the following:

  • MSXB037-05-E2E08-B is designed to provide BNC input signals to xDAP 7400 through its a-Series analog input slots. It is pre-wired for the purpose.
  • Other MSXB037 boards work with xDAP 7400 for user supplied input signal conditioning, quick connect wiring, or discrete wiring to low density DB37 connectors.
  • MSXB065 provides anti-alias filtering with optional amplification.
  • MSXB067 provides strain gauge input with analog input filtering.

The new signal routing notations for the set command are available in the DAPL 3000 version 1.00 release, but these notations should be considered beta release status. Standard configurations without the special notations will be unaffected. The routing notations are not expected to change significantly in future versions of the DAPL 3000 system, or for future members of the xDAP family, but the routing and channel numbering are likely to change. The routing codes could refer to different slot locations or different physical connector devices on different xDAP models. Any changes will be noted in the release notes for DAPL 3000.


The sample DAPstudio configuration Q10053-c1_8.dms reads 8 channels c1:d0 to c1:d7 at 1M s/s (8M s/s aggregate) and displays them in a graph. On an xDAP7400 these channel designations map to J4 and correspond to the first 8 BNC inputs on a typical configuration with MSXB037-05-E2E08-B.

See the DAPL 3000 Supplement for information about special DAPL 3000 configuration commands.

See the xDAP page for information about xDAP 7400.