PXIe-2727 Overview

PXIe-2727 Pinout


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Table 1. Signal Descriptions
Signal Description
Bx+ Positive bank connection
Bx- Negative bank connection
CHx+ Positive signal connection
CHx- Negative signal connection
HI HI input connection
HI SENSE HI sense connection
LO LO input connection
LO SENSE LO sense connection
— No connection

PXIe-2727 Hardware Diagram

This figure shows the hardware diagram of the module.


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Note Resistance values are nominal. Refer to the PXIe-2727 Specifications for resistor values and accuracy information.

Refer to the following list for relay names on the module.

  • kb0r0, kb0r1...kb0r7
  • kb1r0, kb1r1...kb1r7
  • kb2r0, kb2r1...kb2r7
  • kb3r0, kb3r1...kb3r7
  • kb4r0, kb4r1...kb4r7
  • kb5r0, kb5r1...kb5r7
  • kb6r0, kb6r1...kb6r7
  • kb7r0, kb7r1...kb7r7
  • kb8r0, kb8r1...kb8r7
  • kb9r0, kb9r1...kb9r7
  • kb10r0, kb10r1...kb10r7
  • kb11r0, kb11r1...kb11r7
  • kb12r0, kb12r1...kb12r7
  • kb13r0, kb13r1...kb13r7
  • kb14r0, kb14r1...kb14r7
  • kb15r0, kb15r1...kb15r7
  • kb16r0, kb16r1...kb16r7
  • kb17r0, kb17r1...kb17r7
  • kb0...kb17
  • kb0shunt...kb17shunt
  • kbc01, kbc12...kbc1617
  • ktest0, ktest1...ktest9

PXIe-2727 Topology

This figure shows the topology for the module.

Module software name: 2727/Independent (NISWITCH_TOPOLOGY_2727_INDEPENDENT)

The module is composed of reed relays in parallel with discrete resistors. The module has nine channels that can nominally switch from 0 Ω to 16,383 Ω in 0.25 Ω steps.

Note NI has created a set of reference VIs that you can use to specify a desired resistance value to output or RTD temperature to simulate. Using the reference VIs is the simplest way to interact with the programmable resistor module. It is also possible to program using direct calls in NI-SWITCH, NI-DAQmx, NI Switch Executive, or an IVI switch driver. For more information, including a detailed overview of the module architecture, visit ni.com/r/272xoverview.
Note Switching inductive loads, such as motors and solenoids, can produce high-voltage transients in excess of the module's rated voltage. Without additional protection, these transients can interfere with module operation and impact relay life.

Independent Topology


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Note Bank connect relays allow adjacent banks or channels to connect together internally. For example, you can connect two or more adjacent channels together to create a potentiometer, a voltage divider, or a multi-segment resistor chain.

Making a Connection

Each 16-bit channel is composed of two adjacent 8-bit banks on the module. For example, ch0 is composed of banks 0 and 1 and ch1 is composed of banks 2 and 3. NI has created a set of reference VIs that will programmatically open and close relays based on a user-specified resistance value or RTD temperature to simulate. To access these reference VIs, visit ni.com/r/272xoverview.. NI recommends using this set of reference VIs for the easiest programming experience. If not using these reference VIs, NI recommends using the low-level relay control VIs or functions instead of the connect channel VIs or functions. The DAQmx Relay API supports closing multiple relays in a single driver call, which is faster than the channel API.

When a bank relay is closed, the corresponding resistor is placed in parallel with the low resistance of the relay, which nominally equates to a zero Ω shunt. Closing any of the 8 bank relays in a given bank decreases the resistance of that bank.

For example, the following procedure uses the NI-SWITCH Relay API to short across the largest resistor in bank 0 and join bank 0 and bank 1 in series.

  1. Close b0r7 by calling the niSwitch Relay Control VI with the inputs of b0r7 and close.
  2. Close bc01 by calling the niSwitch Relay Control VI with the inputs of bc01 and close.

You can perform the same operation using the NI-SWITCH Channel API, as shown below.

  1. Connect b0->b0r7 by calling niSwitch Connect Channels VI with the inputs of b0 and b0r7.
  2. Connect b0->b1 by calling niSwitch Connect Channels VI with the inputs of b0 and b1.

Each bank is initially in a high impedance (open) state across the bank terminals. To enable the desired output channel you must first connect the bank relay, bN.

Each bank includes a shunt relay that completely bypasses the bank's string of 8 series relays. Closing the shunt relay bN->bNshunt, for example, b0->b0shunt or low-level kb0shunt, results in a low resistance across the bank, 0 Ω nominally. This allows the module to pass signals with minimal attenuation. On 16-bit modules, such as this module, closing the upper bank's shunt relay reduces the resistance when outputting values less than 64 Ω.

Note It is not necessary to close all 8 bank relays and the shunt relay. Configuring multiple banks this way can exceed the power budget of the module.

The 4-pin front panel test connector can connect to any adjacent pair of even-odd banks, allowing resistance measurements, or voltage measurements, across those two banks, for example b0 to b1, b2 to b3, b4 to b5. On 16-bit modules, such as this module, this allows channel resistance measurements using a DMM with Offset Compensated Ohms (such as the PXI-4070, PXI-4071, or PXI-4072). To connect a pair of banks to the test leads, close the appropriate test relays using the command testN->testout. For example, to measure the resistance across banks 0 and 1, call test0->testout and test1->testout. For banks 2 and 3, call test1->testout and test2->testout. Refer to the device's hardware diagram for valid test relay connections.

Note Closing multiple pairs of test relays introduces low impedance paths between banks. NI recommends disconnecting the 37-pin DSUB connector if these low impedance paths would damage your device under test or cause the current specifications of the module to be exceeded.
Note Each channel on the module exhibits an "open" when initialized, reset, and first powered on. The niSwitch Reset and niSwitch Disconnect All Channels VIs or niSwitch_reset and niSwitch_DisconnectAll functions will disconnect all relays, resulting in an open circuit on each channel.

PXIe-2727 Relay Replacement

The module uses reed relays.

Note The module uses a custom lead length to meet safety standards. Trim leads per rework instructions or use one of the custom relays from the relay kit.

Refer to the following table for information about ordering replacement relays.

Replacement Relay Part Number
Coto (all relays) 9117-0001
NI relay kit (10 relays) 781451-10

The module uses lead-free assemblies. Ensure you have the following:

  • Temperature-regulated soldering iron set to 371 °C (700 °F) for lead-free solder rework
  • 96.5/3.0/0.5 Tin/Silver/Copper solder (flux core) for lead-free solder rework
  • Solder wick
  • Fine pick
  • Isopropyl alcohol
  • Cotton swabs
Note The module uses lead-free assemblies. NI recommends using lead-free solder for relay replacement on lead-free assemblies.
Notice Do not rework lead assemblies using a lead-free work station. Lead solder from the unit could contaminate the station.
Notice If a lead-free assembly is reworked with lead solder, label the assembly to indicate this. This can prevent the same unit from being reworked later on a lead-free solder station, which could contaminate the station.

Complete the following steps to disassemble your module and replace a failed relay.

  1. Ground yourself using a grounding strap or a ground connected to your PXI chassis.
    Note Properly grounding yourself prevents damage to your module from electrostatic discharge.
  2. Locate the relay you want to replace. Refer to the following figure and table for relay locations.
    Figure 1. Module Relay Map

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    Relay NameReference DesignatorRelay NameReference DesignatorRelay NameReference DesignatorRelay NameReference Designator
    kb0shunt K1kb4r2 K53kb9shunt K105kb13r2 K157
    kb0 K2kb4r3 K54kb9 K106kb13r3 K158
    kbc01 K3kb4r4 K55 kbc910 K107kb13r4 K159
    ktest0K4kb4r5 K56test5 K108kb13r5 K160
    kb0r0K5kb4r6 K57kb9r0 K109kb13r6 K161
    kb0r1K6kb4r7 K58kb9r1 K110kb13r7 K162
    kb0r2K7kb5shunt K59kb9r2 K111kb14shunt K163
    kb0r3K8kb5K60 kb9r3 K112kb14 K164
    kb0r4K9kbc56 K61kb9r4 K113kbc1415 K165
    kb0r5K10ktest3 K62kb9r5 K114kb14r0 K166
    kb0r6K11kb5r0K63kb9r6 K115kb14r1 K167
    kb0r7K12kb5r1 K64kb9r7 K116kb14r2 K168
    kb1shuntK13kb5r2K65kb10shunt K117kb14r3 K169
    kb1 K14kb5r3K66kb10 K118kb14r4 K170
    kbc12K15kb5r4 K67kbc1011 K119kb14r5 K171
    test1 K16kb5r5K68kb10r0 K120kb14r6 K172
    kb1r0 K17kb5r6K69kb10r1 K121kb14r7 K173
    kb1r1K18kb5r7 K70kb10r2 K122kb15shunt K174
    kb1r2K19kb6shuntK71kb10r3 K123kb15 K175
    kb1r3K20kb6 K72kb10r4 K124kbc1516 K176
    kb1r4K21kbc67K73kb10r5 K125test8 K177
    kb1r5K22kb6r0K74kb10r6 K126kb15r0 K178
    kb1r6K23kb6r1K75kb10r7 K127kb15r1 K179
    kb1r7 K24kb6r2K76kb11shunt K128kb15r2 K180
    kb2shunt K25kb6r3K77kb11 K129kb15r3 K181
    kb2 K26kb6r4K78kbc1112 K130kb15r4 K182
    kbc23 K27kb6r5K79test6 K131kb15r5 K183
    kb2r0 K28kb6r7K80kb11r0 K132kb15r6 K184
    kb2r1 K29kb6r6 K81kb11r1 K133kb15r7 K185
    kb2r2 K30kb7shunt K82kb11r2 K134kb16shunt K186
    kb2r3K31kb7K83kb11r3 K135kb16 K187
    kb2r4 K32kbc78K84kb11r4 K136kbc1617 K188
    kb2r5K33test4K85kb11r5 K137kb16r0 K189
    kb2r6K34kb7r0K86kb11r6 K138kb16r1 K190
    kb2r7 K35kb7r1K87kb11r7 K139kb16r2 K191
    kb3shuntK36 kb7r2 K88kb12shunt K140kb16r3 K192
    kb3K37kb7r3 K89kb12 K141kb16r4 K193
    kbc34K38kb7r4 K90kbc1213 K142kb16r5 K194
    ktest2K39kb7r5 K91kb12r0 K143kb16r6 K195
    kb3r0K40kb7r6 K92kb12r1 K144kb16r7 K196
    kb3r1K41kb7r7 K93kb12r2 K145kb17shunt K197
    kb3r2K42kb8shunt K94kb12r3 K146kb17 K198
    kb3r3K43kb8 K95kb12r4 K147test9 K199
    kb3r4K44kbc89 K96kb12r5 K148kb17r0 K200
    kb3r5 K45kb8r0K97kb12r6 K149kb17r1 K201
    kb3r6K46kb8r1K98kb12r7 K150kb17r2 K202
    kb3r7K47kb8r2 K99kb13shunt K151kb17r3 K203
    kb4shuntK48kb8r3K100kb13 K152kb17r4 K204
    kb4K49kb8r4 K101kbc1314 K153kb17r5 K205
    kbc45K50kb8r5 K102test7 K154kb17r6 K206
    kb4r0K51kb8r6 K103kb13r0 K155kb17r7 K207
    kb4r1K52kb8r7 K104kb13r1 K156——
  3. Remove the front panel, as shown in the following image.
    Figure 2. Removing the Front Panel

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    1. Bracket
    2. Front Panel
    3. Front Panel Overlay
    4. Screws
  4. Remove the bracket, as shown in the following image.
    Figure 3. Removing the Bracket

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    1. CA3 Digital Back End
    2. Bracket
    3. Daughter Card
    4. Screws
  5. Replace the relay as you would any other through-hole part. Trim the replaced relay leads to no more than 1 mm (0.04 in.) from the PCB.
Tip Use the NI-SWITCH Switch Soft Front Panel to reset the relay count after you have replaced a failed relay. Refer to the Switch Soft Front Panel Help for more information.