API Support for Switch Modules
Switch modules can support any of four different ways to control their relays. You may use the APIs interchangeably, but NI recommends using a single API for each application.
- Digital Output—Create your tasks, either programmatically with the Create Channel Digital Output function/VI or interactively through the DAQ Assistant, using the digital output physical channels. Use the digital versions of the Write function/VI to control the relays. Each digital port consists of 32 digital lines, and each line represents a relay on the switch. For example, if a module contains 64 relays, the first 32 are on port 0, and the rest will be on port 1. Writing a 0 to a digital line opens the relay and writing a 1 closes it.
- Immediate—The immediate API, supported by all switches, provides a switch channel-based interaction recommended for nonscanning operations. Functions/VIs such as DAQmx Switch Connect and DAQmx Switch Disconnect are considered part of the immediate API.
- Relay—The relay API provides a relay-based interaction. Functions/VIs like DAQmx Switch Open Relays and DAQmx Switch Close Relays are considered part of the relay API.
- Scanning—Scanning is a method of connecting channels and is often used when connecting instruments and devices under test (DUTs) in a specific order. In this operation mode, the switch cycles through each entry in a scan list downloaded to the switch. The triggers the switch receives initiate this cycling. Create scanning tasks using DAQmx Switch Create Scan List and control tasks using functions/VIs like DAQmx Start, DAQmx Stop, and so on.
Supported Topologies
Every switch module supports one or more topologies. Changing the topology alters the functionality of the switch and, in many cases, changes the list of supported channel names.
Special Considerations
Some switch modules have specific behaviors that you must consider when developing applications, described in the following table.
| Device | Supported APIs | Supported Topologies |
|---|---|---|
| PXI-250124-Channel FET Multiplexer/Matrix |
Immediate Relay Scanning |
2501/1-Wire 48x1 Mux
2501/1-Wire 48x1 Amplified Mux 2501/2-Wire 24x1 Mux 2501/2-Wire 24x1 Amplified Mux 2501/2-Wire Dual 12x1 Mux 2501/2-Wire Quad 6x1 Mux 2501/2-Wire 4x6 Matrix 2501/4-Wire 12x1 Mux |
| PXI-2503 24-Channel Relay Multiplexer/Matrix |
Immediate Relay Scanning |
2503/1-Wire 48x1 Mux 2503/2-Wire 24x1 Mux 2503/2-Wire Dual 12x1 Mux 2503/2-Wire Quad 6x1 Mux 2503/2-Wire 4x6 Matrix 2503/4-Wire 12x1 Mux |
| PXI-2527 32-Channel 300 V Multiplexer |
Immediate Relay Scanning |
2527/1-Wire 64x1 Mux 2527/1-Wire Dual 32x1 Mux 2527/2-Wire 32x1 Mux 2527/2-Wire Dual 16x1 Mux 2527/4-Wire 16x1 Mux 2527/Independent |
| PXI-2529 128-Crosspoint Relay Matrix |
Immediate Relay Scanning |
2529/2-Wire 8x16 Matrix 2529/2-Wire 4x32 Matrix 2529/2-Wire Dual 4x16 Matrix |
| PXI-2530 128-Channel Reed Relay Multiplexer/Matrix |
Immediate Relay Scanning |
2530/1-Wire 128x1 Mux 2530/1-Wire Dual 64x1 Mux 2530/2-Wire 64x1 Mux 2530/4-Wire 32x1 Mux 2530/1-Wire 4x32 Matrix 2530/1-Wire 8x16 Matrix 2530/1-Wire Octal 16x1 Mux 2530/1-Wire Quad 32x1 Mux 2530/2-Wire 4x16 Matrix 2530/2-Wire Dual 32x1 Mux 2530/2-Wire Quad 16x1 Mux 2530/4-Wire Dual 16x1 Mux 2530/Independent |
| PXI-2532 512-Crosspoint Matrix |
Immediate Relay Scanning |
2532/1-Wire 16x32 Matrix 2532/1-Wire 4x128 Matrix 2532/1-Wire 8x64 Matrix 2532/1-Wire Dual 16x16 Matrix 2532/1-Wire Dual 4x64 Matrix 2532/1-Wire Dual 8x32 Matrix 2532/1-Wire Sixteen 2x16 Matrix 2532/2-Wire 16x16 Matrix 2532/2-Wire 4x64 Matrix 2532/2-Wire 8x32 Matrix |
| PXI-2533 256-Crosspoint SSR Matrix |
Immediate Relay Scanning |
2533/1-Wire 4x64 Matrix |
| PXI-2534 256-Crosspoint SSR Matrix |
Immediate Relay Scanning |
2534/1-Wire 8x32 Matrix |
| PXI-2535 544-Crosspoint FET Matrix |
Immediate Relay Scanning |
2535/1-Wire 4x136 Matrix |
| PXI-2536 544-Crosspoint FET Matrix |
Immediate Relay Scanning |
2536/1-Wire 8x68 Matrix |
| PXI-2545 2.7 GHz 4x1 Terminated 50 Ohm Multiplexer |
Immediate Relay Scanning |
2545/4x1 Terminated Mux |
| PXI-2546 2.7 GHz Dual 4x1 50 Ohm Multiplexer |
Immediate Relay Scanning |
2546/Dual 4x1 Mux |
| PXI-2547 2.7 GHz 8x1 50 Ohm Multiplexer |
Immediate Relay Scanning |
2547/8x1 Mux |
| PXI-2548 2.7 GHz 4-SPDT 50 Ohm Relay Module |
Digital Output Immediate Relay Scanning |
2548/4-SPDT |
| PXI-2549 2.7 GHz Terminated 2-SPDT 50 Ohm Relay Module |
Digital Output Immediate Relay Scanning |
2549/Terminated 2-SPDT |
| PXI-2554 2.5 GHz 4x1 75 Ohm Multiplexer |
Immediate Relay Scanning |
2554/4x1 Mux |
| PXI-2555 2.5 GHz 4x1 Terminated 75 Ohm Multiplexer |
Immediate Relay Scanning |
2555/4x1 Terminated Mux |
| PXI-2556 2.5 GHz Dual 4x1 75 Ohm Multiplexer |
Immediate Relay Scanning |
2556/Dual 4x1 Mux |
| PXI-2557 2.5 GHz 8x1 75 Ohm Multiplexer |
Immediate Relay Scanning |
2557/8x1 Mux |
| PXI-2558 2.5 GHz 4-SPDT 75 Ohm Relay Module |
Digital Output Immediate Relay Scanning |
2558/4-SPDT |
| PXI-2559 2.5 GHz Terminated 2-SPDT 75 Ohm Relay Module |
Digital Output Immediate Relay Scanning |
2559/Terminated 2-SPDT |
| PXI-2564 16-SPST Relay Module |
Digital Output Immediate Relay Scanning |
2564/8-DPST 2564/16-SPST |
| PXI-2565 16-SPST Power Relay Module |
Digital Output Immediate Relay Scanning |
2565/16-SPST |
| PXI-2566 16-SPDT Relay Module |
Digital Output Immediate Relay Scanning |
2566/8-DPDT 2566/16-SPDT |
| PXI-2567 64-Channel Relay Driver Module |
Digital Output Immediate Relay Scanning |
2567/Independent |
| PXI-2568 31-Channel SPST Relay Module |
Digital Output Immediate Relay Scanning |
2568/15-DPST 2568/31-SPST |
| PXI-2569 100-Channel SPST Relay Module |
Digital Output Immediate Relay Scanning |
2569/50-DPST 2569/100-SPST |
| PXI-2570 40-Channel SPDT Relay Module |
Digital Output Immediate Relay Scanning |
2570/20-DPDT 2570/40-SPDT |
| PXI-2575 196x1 Relay Multiplexer |
Immediate Relay Scanning |
2575/1-Wire 196x1 Mux 2575/2-Wire 98x1 Mux 2575/2-Wire 95x1 Mux |
| PXI-2576 Multi-Bank Multiplexer |
Immediate Relay Scanning |
2576/2-Wire Octal 8x1 Mux 2576/2-Wire Sixteen 4x1 Mux |
| PXI-2584 High-Voltage Multiplexer |
Immediate Relay Scanning |
2584/Independent 2584/1-Wire 12x1 Mux 2584/1-Wire Dual 6x1 Mux 2584/2-Wire 6x1 Mux |
| PXI-2585 10-Channel Multiplexer |
Immediate Relay Scanning |
2585/1-Wire 10x1 Mux |
| PXI-2586 10-Channel SPST Relay Module |
Digital Output Immediate Relay Scanning |
2586/5-DPST 2586/10-SPST |
| PXI-2590 1.3 GHz 4x1 50 Ohm Multiplexer |
Immediate Relay Scanning |
2590/4x1 Mux |
| PXI-2591 4 GHz 4x1 50 Ohm Multiplexer |
Immediate Scanning |
2591/4x1 Mux |
| PXI-2593 500 MHz Dual 8x1 50 Ohm Multiplexer |
Immediate Relay Scanning |
2593/16x1 Mux 2593/Dual 8x1 Mux 2593/8x1 Terminated Mux 2593/Dual 4x1 Terminated Mux 2593/Independent |
| PXI-2594 1x4 2.5 GHz Multiplexer |
Immediate Relay Scanning |
2594/4x1 Mux |
| PXI-2595 1x4 5.5 GHz Multiplexer |
Immediate Relay Scanning |
2595/4x1 Mux |
| PXI-2596 Dual 1x6 26.5 GHz Multiplexer |
Immediate Relay Scanning |
2596/Dual 6x1 Mux |
| PXI-2597 1x6 26.5 GHz Terminated Multiplexer |
Immediate Relay Scanning |
2597/6x1 Terminated Mux |
| PXI-2598 Dual 26.5 GHz Transfer Switch |
Immediate Relay Scanning |
2598/Dual Transfer |
| PXI-2599 Dual 26.5 GHz SPDT |
Immediate Relay Scanning |
2599/2-SPDT |
| SCXI-1127 32-Channel Relay Multiplexer/Matrix See SCXI-1127 Considerations |
Immediate Relay Scanning |
1127/1-Wire 64x1 Mux 1127/2-Wire 32x1 Mux 1127/4-Wire 16x1 Mux 1127/2-Wire 4x8 Matrix |
| SCXI-1128 32-Channel Solid-State Relay (SSR) Multiplexer/Matrix See SCXI-1128 Considerations |
Immediate Relay Scanning |
1128/1-Wire 64x1 Mux 1128/2-Wire 32x1 Mux 1128/4-Wire 16x1 Mux 1128/2-Wire 4x8 Matrix 1128/Independent |
| SCXI-1129 256-Crosspoint Relay Matrix |
Immediate Relay Scanning |
1129/2-Wire 16x16 Matrix 1129/2-Wire 8x32 Matrix 1129/2-Wire 4x64 Matrix 1129/2-Wire Dual 8x16 Matrix 1129/2-Wire Dual 4x32 Matrix 1129/2-Wire Quad 4x16 Matrix |
| SCXI-1130 256-Channel Reed Relay Multiplexer/Matrix |
Immediate Relay Scanning |
1130/1-Wire 256x1 Mux
1130/1-Wire Dual 128x1 Mux 1130/2-Wire 128x1 Mux 1130/4-Wire 64x1 Mux 1130/1-Wire 4x64 Matrix 1130/1-Wire 8x32 Matrix 1130/1-Wire Octal 32x1 Mux 1130/1-Wire Quad 64x1 Mux 1130/1-Wire Sixteen 16x1 Mux 1130/2-Wire 4x32 Matrix 1130/2-Wire Octal 16x1 Mux 1130/2-Wire Quad 32x1 Mux 1130/4-Wire Quad 16x1 Mux 1130/Independent |
| SCXI-1160 16-SPDT General-Purpose Relay Module |
Digital Output Immediate Relay |
1160/16-SPDT |
| SCXI-1161 8-SPDT Power Relay Module |
Digital Output Immediate Relay |
1161/8-SPDT |
| SCXI-1163R 32-Channel SSR |
Digital Output Immediate Relay |
1163R/Octal 4x1 Mux |
| SCXI-1166 32-SPDT Relay Module |
Digital Output Immediate Relay Scanning |
1166/16-DPDT 1166/32-SPDT |
| SCXI-1167 64-Channel Relay Driver Module |
Digital Output Immediate Relay Scanning |
1167/Independent |
| SCXI-1169 100-Channel SPST Relay Module |
Digital Output Immediate Relay Scanning |
1169/50-DPST 1169/100-SPST |
| SCXI-1175 196x1 Relay Multiplexer |
Immediate Relay Scanning |
1175/1-Wire 196x1 Mux
1175/2-Wire 98x1 Mux 1175/2-Wire 95x1 Mux |
| SCXI-1190 1.3 GHz Quad 4x1 50 Ohm Multiplexer |
Immediate |
1190/Quad 4x1 Mux |
| SCXI-1191 4 GHz Quad 4x1 50 Ohm Multiplexer |
Immediate |
1191/Quad 4x1 Mux |
| SCXI-1192 18 GHz 8-SPDT 50 Ohm Relay Module |
Digital Output Immediate Relay |
1192/8-SPDT |
| SCXI-1193 500 MHz Quad 8x1 50 Ohm Multiplexer |
Immediate Relay Scanning |
1193/32x1 Mux 1193/Dual 16x1 Mux 1193/Quad 8x1 Mux 1193/16x1 Terminated Mux 1193/Dual 8x1 Terminated Mux 1193/Quad 4x1 Terminated Mux 1193/Independent |
| SCXI-1194 Quad 1x4 2.5 GHz Multiplexer |
Immediate Relay Scanning |
1194/Quad 4x1 Mux |
| SCXI-1195 Quad 1x4 5.5 GHz Multiplexer |
Immediate Relay Scanning |
1195/Quad 4x1 Mux |
SCXI-1127 Considerations
To route signals to the analog bus backplane, you must enable the switch device property Auto Connect Analog Bus. As a result, if you connect a channel (ch1) to the common channel (com0), the signal is automatically routed from com0 to the analog bus (ab0).
The SCXI-1127 supports only continuous scanning.
If you have used immediate or relay operations to change relay states before starting a scan, all of those relays are opened when the scan starts. After the scan completes, the relays are returned to their previous state prior to the scan.
Early revisions of this hardware reserve the SCXI_TRIG1 line. If you place an older revision of this hardware (earlier than revision E) into an SCXI chassis that also contains an SCXI analog input module that performs track and hold (such as the SCXI-1140 or SCXI-1520), you may get reservation errors when trying to use the SCXI analog input module.
SCXI-1128 Considerations
To route signals to the analog bus backplane, you must enable the switch device attribute/property Auto Connect Analog Bus. As a result, if you connect a channel (ch1) to the common channel (com0), the signal is automatically routed from com0 to the analog bus (ab0).
The SCXI-1128 supports only continuous scanning.
If you have used immediate or relay operations to change relay states before starting a scan, all of those relays are opened when the scan starts. After the scan completes, the relays are returned to their previous state prior to the scan.