NI SwitchBlock Device Reference

NI Switches Help

Edition Date: April 2015

Part Number: 375472H-01

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An NI SwitchBlock device represents one or more NI SwitchBlock cards that are configured in software to function as a device.

Note Note  All NI SwitchBlock devices are programmed in the same manner regardless of the number of NI SwitchBlock cards that compose them.

Refer to the following sections for guidelines and requirements when configuring your cards to function as devices.

NI SwitchBlock Card Types

Each card is available in two types, type A and type B, which vary only in the signals they route to the front panel connector. The letter at the end of the card model indicates the type of card. For example, NI 2810A indicates a type A card, and NI 2810B indicates a type B card. Refer to the following figure and table for differences between card types.

The following image represents a 1-wire device.

The following image represents a 2-wire device.

Card Type Characteristics
A Front connector pins connect to all analog bus channels and columns of the matrix. Type A cards directly route analog bus lines on the NI SwitchBlock carrier to the front connector.
B Front connector pins connect only to the columns of the matrix.

Card Combination Use Cases

Create a multicard device according to the requirements for multicard devices when a single-card device cannot support the size of your application. Refer to the following use cases to decide how to compose your multicard device.

Card Combination Use Cases
One Type A Card + One or More Type B Cards Recommended when an application requires direct access to the analog bus channels. Typical usage of this card combination involves connecting analog bus channels to columns.
All Type B Cards Recommended when connecting only to columns. Analog bus channels may still be used for signal routing as needed, but they will not be routed to the front panel I/O connector.
Note Note  Using all type A cards is not recommended. Using multiple type A cards in an NI SwitchBlock system duplicates connections to the same analog bus lines and reduces signal integrity.

Requirements for Multicard Devices

  • While different card models may be installed and operated in the same NI SwitchBlock carrier, a device may only be composed of cards of the same model. For example, you can combine two NI 2811A/B cards into one device, but if you install an NI 2811A/B and an NI 2816A/B, you will have to operate them as separate devices.
  • All cards in a multicard device must be installed in the same NI SwitchBlock carrier. If your switching system spans multiple carriers, NI recommends using NI Switch Executive to manage all cards as a single virtual device. Refer to the NI Switch Executive Help for information about creating virtual devices.
  • While multicard devices may be composed of any combination of type A and type B cards, NI recommends reducing the total number of paths you expose a signal to by using no more than one type A card in an NI SwitchBlock system. Refer to the Card Combination Use Cases section of this help topic for more information about recommended card combination options.

Refer to the device book for your card in the NI Switches Help for information about card combinations for specific topologies.

Topologies of Multicard Devices

The topology of a multicard device is the merger of the topologies of each individual card. The number of columns in a multicard device can be determined by multiplying the number of cards combined by the number of columns on one card.

For example, the topology of a single NI 2810A/B card is a 1-Wire 4×43 matrix. If you create a multicard device using three NI 2810A/B cards, 43 columns multiplied by three cards would total 129 columns in the multicard device. The resulting topology for the multicard device would be a 1-Wire 4×129 matrix. Each card maintains its own row channels, and the analog bus channels are used to connect channels in different cards.

Channel Naming for NI SwitchBlock Devices

Refer to the following images and instructions to determine the row, column, and analog bus channel names for your NI SwitchBlock device.

Row Channel Names

Row channel names are composed of the card number followed by the row number, written in the format, cardXrY, where X indicates the card number and Y indicates the row number. Card numbers correspond to the position of the card in relation to the other cards composing the device, starting with 1 for the leftmost card in the device.

Note Note  The card number does not always correspond with the carrier slot number for the installed card. For instance, when the leftmost card in your device is installed in the third slot of the carrier, this card will still be numbered card1.

Column Channel Names

Column channel names are written in the format cZ, where Z indicates the column number. In multicard devices, column numbers for each card resume where the columns for the previous card in the device ended, with column numbers for the leftmost card starting at zero. In separate SwitchBlock devices, column numbers start at c0 for the first relay card.

Analog Bus Channel Names

Analog bus channels connect the rows to the carrier analog bus. Analog bus channel names are written in the format abX, where X indicates the analog bus channel number and corresponds to the adjacent row channel. All relay cards within the same carrier, or within multiple carriers connected using an expansion bridge, connect to the same analog bus through their analog bus channels regardless of which NI SwitchBlock device they are in.

Relay Naming for NI SwitchBlock Devices

Refer to the following instructions to determine the relay names for your NI SwitchBlock device.

Matrix Relays

Matrix relay names for NI SwitchBlock 1-wire cards follow the format of kcardXrYcZ, where cardXrY indicates the name of the row channel that connects at that relay and cZ indicates the name of the column channel that connects at that relay. For example, a relay that connects card1r5 and c18 would be named kcard1r5c18. A relay that connects card2r2 and c44 would be named kcard2r2c44.

Matrix relay names for NI SwitchBlock 2-wire cards with SPST relays follow the formats of kcardXrYcZw0 and kcardXrYcZw1 for each wire on the channel.

Analog Bus Relays

Analog bus relay names for NI SwitchBlock 1-wire cards follow the format of kcardXabY, where cardX indicates the card number and abY indicates name of the analog bus channel that the relay connects to a corresponding row. For example, the relay that connects ab2 to card1r2 would be named kcard1ab2.

Analog bus relay names for NI SwitchBlock 2-wire cards with SPST relays follow the formats of kcardXabYw0 and kcardXabYw1 for each wire.

Note Note  All NI SwitchBlock cards attach to the same physical analog bus regardless of whether they are 1-wire or 2-wire devices. However, the specific analog bus line(s) that an analog bus channel connects to differs between 1-wire and 2-wire cards. For example, ab0 for a 1-wire device connects to analog bus line 0 by closing kcard1ab0 while ab0 for a 2-wire device connects to analog bus lines 0 and 1 by closing kcard1ab0w0 and kcard1ab0w1.


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