NI SCXI-1193 Reset Algorithms

The NI SCXI-1193 uses coupled SPDT relays to provide flexible routing and multiple configurations. This architecture allows the commons of each bank to be connected for further signal routing options. If two or more signal generators are connected to the commons (COM<0..3>), avoid connecting the output terminals, as this could damage the signal generators. Consult your signal source documentation for more information.

Two reset algorithms are used to reduce the chances of inadvertently connecting channels or commons during software resets, disconnecting all channels, changing topologies, or aborting scans. These algorithms are provided in the following sections as a reference.

Note  During chassis power on, the NI SCXI-1193 opens all relays, returning to the quad 8x1 multiplexer topology. In this scenario, neither of the following algorithms are used.

In the following algorithms, OPEN refers to the power-on state of the relay as represented in the quad 8x1 multiplexer topology. RESET refers to the final state of the relay after the algorithm completes.

Simple Reset Algorithm

The simple reset algorithm restores the switch to its initial state after aborting a scan and during a call to niSwitch_DisconnectAll. This algorithm is not used in the independent topology.

1. Open all KA relays to disconnect any signals at the channel terminals.
2. Wait for relay settling time.
3. Actuate all other relays as necessary. The simple algorithm is never used when changing topologies. Therefore, KD relays will not actuate in a way that can short the COMs.
4. Wait for relay settling time.
5. Reset KA relays as necessary
6. Wait for relay settling time.

Advanced Reset Algorithm

The advanced reset algorithm is used with all topologies for software reset, and for changing between topologies. This algorithm is used for disconnecting all channels and is also used after aborting a scan to restore the switch to its initial state in the independent topology.

1. Open all KA relays to disconnect any signals at the channel terminals.
2. Wait for relay settling time.
3. Reset all KB relays.
4. Reset all KC relays.
5. Ensure that both relays in each of the following relay pairs are OPEN or CLOSED. To determine their state, use niSwitch Query a Single Switch. If the relays in each pair are mismatched, actuate one of the relays.

   KD0, KD1

   KD4, KD5

   KD6, KD7

   KD10, KD11

6. Wait for relay settling time.
7. If KD0, KD1, KD4, KD5, KD6, KD7, KD10, and KD11 are not in their respective reset positions, continue to the next step. Otherwise, reset KD2, KD3, KD8, KD9, and skip to step 18.
8. Set KD2 and KD8 to OPEN.
9. Set KD3 and KD9 to their reset position.
10. Wait for relay settling time.
11. Set KD0, KD1, KD4, KD5 to their reset position.
12. Wait for relay settling time.
13. Set KD6, KD7, KD10, KD11 to their reset position.
14. Wait for relay settling time.
15. Set KD2 and KD8 to their reset position.
16. Wait for relay settling time.
17. Reset KA relays as necessary
18. Wait for relay settling time.