# A guide to relay-based elevator control
> This page covers relay-based elevator control in Salto KS, including required hardware, floor setup, relay output mapping, and access group configuration.


## What is relay-based elevator control in Salto KS? {#what-is-relay-based-elevator-control-in-salto-ks}

Relay-based elevator control allows building managers to control which floors users can reach by elevator.
When a user presents an authorized credential to a Salto Wall Reader inside the elevator, only the buttons for the floors that the user has access to become active.

The elevator control panel connects to a Salto BLUEnet Door Controller, also known as a control unit or CU, through relay outputs on one or more Salto Expansion Boards.

## What are the main benefits of relay-based elevator control? {#what-are-the-main-benefits-of-relay-based-elevator-control}

Relay-based elevator control provides Salto KS users with:

- **Floor-level access management**: manage access by floor rather than only by individual lock.
- **Flexible access**: manage floors with or without associated locks.
- **Streamlined commissioning**: configure floors, relay outputs, and access groups in the Larry Commissioning web app.
- **Scalable hardware**: a CU Compact controls up to 66 relay outputs through its main board and connected Expansion Boards.
- **Salto technical support**: every component belongs to the Salto smart locking ecosystem, so Salto provides technical support without a third-party elevator control provider.

## How does relay-based elevator control work? {#how-does-relay-based-elevator-control-work}

Each elevator button that forms part of the elevator control configuration connects to a relay output associated with a specific floor.
A Salto Wall Reader sits inside the elevator and connects to the CU.

When a user presents their credential:

1. The CU communicates with the Salto IQ over Bluetooth.
2. The system retrieves the user's access rules.
3. The relays associated with the user's authorized floors activate.
4. The corresponding elevator buttons become active.

## What Salto hardware do you need for relay-based elevator control? {#what-salto-hardware-do-i-need-for-relay-based-elevator-control}

Relay-based elevator control uses the following Salto hardware:

- A Salto IQ.
- A Salto BLUEnet Door Controller, also known as a CU.
- A Salto Wall Reader.
- One or more Salto Expansion Boards, depending on the number of relay outputs you need.

Wire the elevator control panel to the relay outputs on the CU main board and the Expansion Boards.

## What are the supported hardware and firmware versions? {#what-are-the-supported-hardware-and-firmware-versions}

The hardware requirements for relay-based elevator control are:

- **Salto IQ**: `FwNum 27.x` or higher.
- **Salto BLUEnet Door Controller (CU)**: `v02.20`, `FwNum0216`, `CUC1B0`.
- **Salto Expansion Board**: `v01.01`, `FwNum0162`, `CUCEB004`, or `v01.01`, `FwNum0161`, `CUCEB122`.

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Install the CU and the Expansion Board within 1 m of each other.
This limit comes from the maximum supported length of the bus cable that connects the two devices.
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## Which Salto KS subscription do I need? {#which-salto-ks-subscription-do-i-need}

Relay-based elevator control is available to Salto KS customers with an active [**Pro** package subscription](/ks/account/subscription-and-vouchers).

## Where do I configure relay-based elevator control? {#where-do-i-configure-relay-based-elevator-control}

An installer performs the initial configuration in the Larry Commissioning web app while the site is in installer mode.

The configuration consists of:

1. Creating the floors.
2. Associating locks with floors, where applicable.
3. Configuring the relay outputs.
4. Creating access groups and assigning tags, locks, floors, and timeframes.
5. Releasing the site to the site admin.

After the installer releases the site, site admins can still edit some of the access group configuration in the Salto KS web app.

## What is a floor in Salto KS? {#what-is-a-floor-in-salto-ks}

A floor represents an actual level of a building.
Floors organize locks and access rights so that you can manage elevator access at floor level.

Each floor has a name and a unique floor number.
You can associate multiple locks with one floor, but an individual lock can belong to only one floor.

## Which floor numbers can I configure? {#which-floor-numbers-can-i-configure}

Floor numbers range from -10 to 100:

- **0** represents the ground floor.
- **-10** to **-1** cover underground floors, such as parking levels.
- **1** to **100** cover floors above ground.

Each floor number must be unique, and you can assign it to only one floor.

## Does every floor need an associated lock? {#does-every-floor-need-an-associated-lock}

No.
You can create a floor without an associated lock.
This helps with a shared facility, such as a gym or a swimming pool, where the elevator opens directly onto the floor or area.

To give users access to a floor without an associated lock, add the floor directly to the relevant access group.

## How do I create a floor? {#how-do-i-create-a-floor}

To create a floor, log in to the Larry Commissioning web app and follow these steps:

1. Go to **Installations** and select the site.
2. Select **Floors**.
3. Select **Create a floor**.
4. Enter a floor name.
5. Select a unique floor number between -10 and 100.
6. Select the locks to associate with the floor, or select **No lock associated with this floor**.
7. Select **Next** to create the floor.

The new floor then appears on the site's **Floors** page.

## What is the relay output capacity of a CU Compact? {#what-is-the-relay-output-capacity-of-a-cu-compact}

A CU Compact main board has two relay outputs and supports up to 16 connected Expansion Boards.
Each CUCEB004 Expansion Board has four relay outputs, so a CU Compact with 16 CUCEB004 boards controls up to 66 relay outputs in total.

One CU Compact connects to one Wall Reader.

## Which CU output function do I use for elevator control? {#which-cu-output-function-do-i-use-for-elevator-control}

For relay-based elevator control in Salto KS, select **Control** as the relay output function and assign the relevant floor to the relay.

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This configuration is specific to the Salto KS elevator control use case.
It differs from the standard configuration described for Salto Space, where you select a lock and configure the relay as **Strike**.
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## How do I associate relay outputs with floors? {#how-do-i-associate-relay-outputs-with-floors}

To associate relay outputs with floors, log in to the Larry Commissioning web app and follow these steps:

1. Open the relevant site and select **Hardware**.
2. Locate the Wall Reader in the installed hardware tree.
3. Open the three-dot menu next to the Wall Reader.
4. Select **Lock settings**.
5. Expand **Output Configuration**.
6. Locate the required relay.
7. Set its function to **Control**.
8. Select an existing floor, or create a new floor from the floor menu.
9. Save the changes.

You can associate each relay with only one floor, and each floor with only one relay within a single CU.

## Why are the Expansion Boards not visible in Larry Commissioning? {#why-are-the-expansion-boards-not-visible-in-larry-commissioning}

After you connect the Expansion Boards, press the **Clear** button on the Salto CU.
The boards appear in Larry Commissioning only after you have done this.

If the boards still do not appear, remove and reconnect the power from both the CU and the connected Expansion Boards, and then try again.
If the problem persists, contact your local Salto Support team.

## Should every elevator button connect to a relay? {#should-every-elevator-button-connect-to-a-relay}

No.
If a floor must remain accessible to everyone at all times, do not wire the corresponding elevator button to a CU relay.

For example, the ground-floor button may need to remain available so that users can leave the building at any time.
A button that you do not wire to a relay falls outside Salto KS access rules and remains available to all users.

## How do access groups manage floor access rights? {#how-do-access-groups-manage-floor-access-rights}

An access group can contain:

- Tags.
- Locks.
- Floors.
- A timeframe.

Adding a floor directly to an access group gives the users in that group elevator access to the floor.
Adding a lock that you have already associated with a floor also gives users access to the corresponding floor.

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Access to a floor does not provide access to every lock on that floor.
You must still add a lock to the access group if users need to open it.
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## How do I create an access group for relay-based elevator control? {#how-do-i-create-an-access-group-for-relay-based-elevator-control}

To create an access group for relay-based elevator control, log in to the Larry Commissioning web app and follow these steps:

1. Open the relevant site and select **Access groups**.
2. Select **Create access**.
3. Enter a unique access group name.
4. Select the tags to include.
5. Select the locks to include, where applicable.
6. Select the floors to include.
7. Define the timeframe during which the access rights are valid.

A site admin can also add tags, locks, and floors later in the Salto KS web app, after the installer releases the site.

## What is explicit floor access? {#what-is-explicit-floor-access}

Explicit floor access applies when you add a floor directly to an access group.
Users in that access group receive elevator access to the floor, regardless of whether they have access to a lock on that floor.

For example, if an elevator opens directly into a shared gym with no entrance lock, add the gym floor directly to the residents' access group.

## What is implicit floor access? {#what-is-implicit-floor-access}

Implicit floor access comes through a lock that you have associated with a floor.
When you add that lock to an access group, users in the group receive access to both the lock and the floor on which it sits.

For example, giving a resident access to their apartment lock also gives them elevator access to the floor associated with that lock.

## Does floor access provide access to all locks on that floor? {#does-floor-access-provide-access-to-all-locks-on-that-floor}

No.
Giving a user access to a floor enables access to that floor through the elevator, but it does not give the user access to every lock associated with the floor.

Add any lock that the user needs to open to the relevant access group.

## Can several locks be associated with the same floor? {#can-several-locks-be-associated-with-the-same-floor}

Yes.
You can associate multiple locks with the same floor.
However, each individual lock belongs to only one floor.

## Can one relay be associated with several floors? {#can-one-relay-be-associated-with-several-floors}

No.
One relay controls only one floor, and within a single CU each floor maps to only one relay.

For sites with more than one elevator, each elevator connects to a different CU, and each CU has its own independent floor-to-relay mapping.
In this case, the same floor can map to multiple relays, each one belonging to a different CU.

## Can I limit access to a floor to certain times? {#can-i-limit-access-to-a-floor-to-certain-times}

Yes.
Each access group includes a main timeframe, which determines the days and times when its access rules apply.

The timeframe types available in the commissioning flow include:

- **Custom timeframe**
- **Check-in and check-out**
- **Always**

## What happens when the installer releases the site? {#what-happens-when-the-installer-releases-the-site}

Once the relay outputs and floor mappings are in place, the installer can release the site to the site admin.

The site admin receives an invitation and must accept the Terms of Service when first signing in to Salto KS.
After the transfer of site ownership:

- The site becomes active for the site admin.
- The installer loses their permissions.
- The installer no longer sees the site in Larry Commissioning.

## Can a site admin complete the configuration after the site is released? {#can-a-site-admin-complete-the-configuration-after-the-site-is-released}

A site admin can complete the remaining access management tasks in the Salto KS web app, including associating locks with floors and creating or updating access groups.

However, relay output configuration remains available only in Larry Commissioning.
A site admin cannot complete or modify it in the Salto KS web app.

## Can I change relay output settings in Larry Support? {#can-i-change-relay-output-settings-in-larry-support}

No.
Relay settings are read-only in Larry Support, which supports technicians who monitor, diagnose, and maintain live sites and hardware.
You can view the existing configuration, but you cannot add or edit relay settings.

To change the relay configuration, an installer needs access to the site in Larry Commissioning, which supports installers who set up hardware and create sites.

## What happens if the IQ loses its internet connection? {#what-happens-if-the-iq-loses-its-internet-connection}

If the IQ loses its internet connection to the Salto KS platform, it continues to manage access rules locally using the data it collected last, as long as the CU can still reach the IQ over Bluetooth.

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If the CU cannot connect to the IQ over Bluetooth, the Expansion Board relays cannot activate in [offline access](/ks/general/offline-access) mode.
In that situation, only floors whose elevator buttons are not wired to CU relays, such as the ground floor, remain accessible.
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