> For the complete documentation index, see [llms.txt](https://docs.spiroq.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.spiroq.com/en/guides/navody/payments/mincovnik.md).

# Coin changer and bills

Cash goes through a coin changer (and optionally a bill validator) connected to the MDB payment board.

## Connection

Connect the coin changer with a cable to the MDB payment board. The cable is usually brought out on the inside of the cabinet door. Usually it is enough to plug in the cable and run the test below — the ports should already be set from the installation wizard.

## Test

1. Open the [service menu](/en/guides/navody/everyday-operation/servisni-menu.md) → **Payments**.
2. Device detection starts automatically. The coin changer should show as active.
3. On the customer screen (the sales grid), insert coins, add a product to the cart, and finish the purchase by choosing cash payment.
4. In the Hub, in the machine detail on the **Sales** tab, check that the sale arrived.

The payment port should be configured from the [first-run wizard](/en/guides/navody/getting-started-and-installation/pruvodce.md) at the **Serial ports** step. If the coin changer still shows as inactive in Service menu → **Payments**, check the payment port in Service menu → Device settings → **Machine type**, **Ports** tab. Then check detection again.

On spiral machines, Service menu → **Payments** also has **Reset MDB bus** — use it when the reader or the coin changer stops answering, and then repeat detection.

The machine detail header in the Hub shows whether the Hub last saw the coin changer. When a device that was working on the machine stops answering, a record is created on the **Errors** tab.