Card Payment with SumUp Solo (Terminal Type "SumUp Reader")¶

The SumUp Solo is a card reader that connects to the internet by itself over Wi-Fi or mobile data. DiKAS controls it through the SumUp cloud: the till sends the amount to SumUp, the amount appears on the Solo, the guest pays – and DiKAS books the payment as soon as SumUp confirms it. No IP address, no hardware agent and no router port forwarding are needed. This page leads from the SumUp credentials to the first test payment and explains what to watch for with voids, tips and the end-of-day close.

Some texts appear in German

The SumUp tab, its field names, and the messages that come from the server or from SumUp are shown in German in every language. They are quoted here exactly as they appear, followed by a translation.

Supported Devices¶

Device	Connection in DiKAS	Status
SumUp Solo (Wi-Fi/mobile data)	Terminal type SumUp Reader, paired with a pairing code via the SumUp cloud	✅ Supported
Several Solo per SumUp account	One terminal in DiKAS per device	✅ Supported
SumUp Air (Bluetooth)	—	❌ Not supported at the moment
Phone or tablet as card reader (SumUp Tap to Pay)	—	❌ Not supported at the moment

DiKAS offers other routes for a phone or tablet as card reader, for example Softpay. The overview under Hardware → Card Terminals shows which solution fits your business.

Countries and currency

Whether and where SumUp offers and activates the Solo is decided by SumUp. DiKAS books in the currency entered in the SumUp tab (for example EUR or CHF). If the field is empty, the main currency of the business applies. For Swiss businesses SumUp is listed in the overview of payment terminals.

Requirements¶

A set-up merchant account that SumUp has activated.
A SumUp Solo with internet access (Wi-Fi, optionally mobile data – SumUp activates mobile data separately).

Four details from the SumUp account:

Detail	What it is	Field in DiKAS
API key	Secret key, starts with `sup_sk_`	API-Key
Merchant Code	Identifier of the merchant account, e.g. `MXXXXXXX`	Merchant Code
Affiliate Key	Key for the application assignment	Affiliate Key
App ID	The application identifier entered at SumUp when the Affiliate Key was created	Affiliate App-ID

A user with access to Admin → Settings.
To show the device state in DiKAS: Solo firmware 3.3.39.0 or later. To cleanly end a cancelled payment on the Solo: 3.3.28.0 or later. Older firmware keeps working, just without these extras.

Affiliate Key and App ID belong together

For payments on the Solo, Affiliate Key and Affiliate App-ID must both be entered completely. The App ID is neither the Merchant Code nor a terminal or reader ID, but exactly the value used when the Affiliate Key was created at SumUp. Pairing the Solo does not need the Affiliate Key, but every payment does.

Where in the SumUp account?

API key and Affiliate Key are created in the SumUp developer area (developer.sumup.com). Note the App ID right away.

Setting Up in 7 Steps¶

Keep this order

The SumUp tab appears in the settings only after a terminal of type SumUp Reader has been saved. That is why the terminal comes first. If the tab does not show up right away, reload the page once.

Create the terminal: open Admin → Settings → Hardware → Payment options and choose Add terminal.
Give it a unique Name (for example "Solo Bar 1"), choose SumUp Reader under Type and Save. DiKAS switches off Terminal has its own printer by itself – the Solo does not print, the till prints the card receipt.
Enter the credentials: open Admin → Settings → Hardware → SumUp. Enter API-Key, Merchant Code, Affiliate Key, Affiliate App-ID and Währung (currency). Click Speichern (Save) at the top right and wait for the message "SumUp-Konfiguration gespeichert" (SumUp configuration saved). The API key is stored encrypted and not displayed again; afterwards the field only shows "(gesetzt)" (set).
Connect the Solo to Wi-Fi: switch the Solo on. If it is still logged in to a SumUp account, log out via Settings → About → Log out – a logged-in device cannot be paired. Then open Connections → Wi-Fi in the top menu, choose the business Wi-Fi and enter the password.
Create the pairing code: on the Solo choose Connections → API → Connect in the top menu. The device shows a pairing code that is valid for only about 5 minutes. It has 8 or 9 characters.
Pair in DiKAS: back in Hardware → Payment options, click Pair reader (link icon) in the terminal's row. In the "Pair SumUp reader" window enter the code and choose Pair. DiKAS saves the terminal before pairing, calls SumUp and enters the Reader-ID assigned by SumUp in the field of the same name. Then "Reader gekoppelt und gespeichert: …" (Reader paired and saved) appears.
Check: in the terminal's row choose Check status (Wi-Fi icon). Green means: paired and online. Then make a small test payment – the amount must appear on the Solo, and after a successful payment DiKAS closes the receipt.

After an update

If DiKAS was just updated or restarted, reload the page once and check the SumUp details before testing a payment.

Network

The Solo connects outwards (encrypted, port 443). A guest Wi-Fi is enough as long as it has internet. The Solo cannot cope with a login page (captive portal) or a strongly filtering Wi-Fi – use another Wi-Fi or mobile data then. If both Wi-Fi and mobile data are available, the Solo uses Wi-Fi. Till and Solo do not have to be in the same network; both only need internet.

Solo already paired in the SumUp account?

If the Solo is already paired in the SumUp account, its reader ID can also be entered directly in the Reader-ID field of the terminal row. DiKAS removes spaces at the edges when saving.

Several Solo and Several Tills¶

One SumUp account can pair several Solo, and they can process payments at the same time:

Enter the credentials only once in the SumUp tab – they apply to all Solo of the account.
Create one terminal per Solo in Hardware → Payment options (type SumUp Reader, unique name such as "Solo Terrace") and pair each Solo separately. Always create the pairing code fresh on the respective device.
Assign the terminal to the till:
- centrally per workstation under Admin → Settings → Operations → Workstations, field EC-Terminal (the tab only appears when workstations are active), or
- directly on the device in the till settings, field Terminal (choices: Default (name), a specific terminal or -- No terminal --).
Choice at every payment: if several staff members share several terminals on one device, Choose the terminal for every card payment in the till settings puts a selection in front of the payment. Offer in the selection defines which terminals this device offers. The setting applies to that device only.
For each Solo run Check status and a small test payment and verify that the amount appears on the right Solo.

Without its own choice, a device takes payments through the business's default terminal. Several tills may share one Solo; however, a Solo accepts only one payment at a time. Where tills take payments simultaneously, each workstation needs its own Solo.

Every Solo needs its own reader ID

If a terminal entry is copied, it takes over the reader ID of the original – two tills would then address the same Solo. DiKAS saves it anyway, but after saving it shows the notice "Dieselbe SumUp-Reader-ID ist an mehreren Terminals hinterlegt …" (the same SumUp reader ID is stored on several terminals), and Check status shows a yellow warning icon with "Reader-ID auch an Terminal … hinterlegt". Pair the Solo again on the copied terminal.

How a Payment Works¶

When paying, choose card payment. With several terminals, choose the terminal first.
The Card payment dialog names the terminal at the top and shows "Processing …" with the note "Please present or insert the card at the terminal". At the same time the amount appears on the Solo.
The guest taps or inserts the card or enters the PIN. DiKAS asks SumUp for the result about every 2 seconds, for at most 120 seconds.
On success the dialog shows "Payment successful" with the transaction ID; DiKAS books the payment and closes the receipt. If the payment is declined, the dialog reports "Payment declined".

Card receipt: the Solo has no printer of its own. With Terminal has its own printer switched off (how DiKAS sets it when creating the terminal), the till prints the card receipt on the receipt.

Tips: a tip entered on the Solo is not reported back to the till by SumUp. Enter the tip at the till before starting the card payment.

Cancel or timeout: if the till cancels the payment or the wait time runs out, DiKAS ends the process on the Solo (firmware 3.3.28.0 or later) and asks SumUp for the result once more. If the payment went through at that very moment, DiKAS books it – the card is never charged without a receipt being created. If the amount stays on the Solo anyway (for example because the Solo is offline), check in the SumUp dashboard whether the payment went through.

Voids, Credits and End of Day¶

Action	How it works with SumUp
Void of a receipt with card payment	Void the receipt under Menu → Invoices. DiKAS refunds the card with reference to the original SumUp transaction. Without that reference the process ends in a visible clarification case and nothing is booked.
Card credit without original payment	Not possible. SumUp only refunds an existing payment. DiKAS reports: "Eine referenzlose Karten-Gutschrift ist bei SumUp nicht möglich – bitte über die SumUp-App/das SumUp-Dashboard erstatten." (A card credit without reference is not possible with SumUp – please refund via the SumUp app/dashboard.) Alternatively void the original receipt.
End of day / cash-up at the terminal	Not applicable. DiKAS reports: "SumUp kennt keinen Kassenschnitt – Auszahlungen laufen automatisch (SumUp-Dashboard)." (SumUp has no terminal cash-up – payouts run automatically.) The payouts from SumUp appear in the SumUp dashboard.

More on voids and credits: Payment methods and Receipts.

Limits¶

Only the SumUp Solo via the SumUp cloud; Bluetooth readers and a phone as card reader are not part of this route.
Internet at the till and the Solo is required – without internet there is no card payment on this terminal.
No card credit without original payment, no cash-up on the device.
Tips from the device are not carried over into the till.
A payment waits 120 seconds at most for the result.
The amount is rounded to two decimal places (none for CLP, COP and HUF) and must be greater than 0.

Errors and Remedies¶

What you see	Cause and remedy
"SumUp-Zugang abgelehnt: Bitte einen aktiven API-Secret-Key (sup_sk_…) aus dem SumUp-Händlerkonto prüfen." (SumUp access denied)	The API key is invalid, revoked or not a secret key. Check an active key (`sup_sk_…`) in the SumUp developer area and enter and save it again in the SumUp tab.
"Der hinterlegte SumUp-API-Schlüssel enthält ein Zeichen, das nicht übertragen werden kann …" (the stored key contains a character that cannot be transmitted)	A non-breaking space or special character was copied along. Paste the key into the SumUp tab again.
"SumUp Fehler: BadRequest" when pairing	SumUp rejected the request – usually the pairing code is expired or wrong. Restart Connections → API → Connect on the Solo and enter the new code immediately.
Pairing code is not accepted	The code is valid for only about 5 minutes, or the Solo is still logged in. Log out on the Solo via Settings → About → Log out, restart Connections → API → Connect and pair in DiKAS immediately.
"SumUp-Terminal … ist nicht konfiguriert (API-Key/Merchant-Code in den Einstellungen oder Reader-ID am Terminal fehlt)."	The SumUp tab lacks the API key or Merchant Code, or the terminal has no reader ID because it was not paired yet. Complete the details, save and pair the Solo.
"SumUp Affiliate-Key und Affiliate App-ID fehlen …" (Affiliate Key and App ID missing)	Enter both values in the SumUp tab, explicitly click Speichern (Save) and only then pay.
"SumUp-Terminal … nicht gefunden." (terminal not found)	The terminal is not saved or was deleted. Check name and type in Hardware → Payment options, save and pair again.
"Reader … nicht gefunden." (Check status)	The reader ID does not belong to the SumUp account. Check the entered ID or pair the Solo again.
"Kopplung abgelaufen – Leser neu pairen …" (pairing expired)	The pairing code was confirmed too late. Create a new code on the Solo and pair again in DiKAS with Pair reader.
"Kopplung am Gerät noch nicht bestätigt – den Pairing-Code am Solo bestätigen, dann erneut prüfen." (not yet confirmed on the device)	Pairing was started but not completed on the Solo. Confirm the code on the device, then Check status.
"Leser ist offline – WLAN am Solo (Connections → Wi-Fi) prüfen." (reader is offline)	The Solo has no internet connection. On the Solo check that the Wi-Fi is connected (internet, not just a network) and restart the device if needed. Then Check status.
"SumUp Fehler: UnprocessableEntity" during a payment	SumUp rejects the request, for example because the Solo is offline. Check status, check the Wi-Fi on the Solo and restart the payment.
"SumUp: Timeout – keine Antwort vom Reader." (no answer from the reader)	No result after 120 seconds. Check the Solo and internet. If the guest paid anyway, DiKAS books the payment itself during the re-check; when in doubt look in the SumUp dashboard before charging again.
"SumUp Zahlung FAILED." (also EXPIRED, CANCELLED)	The Solo ended the process, for example because the card was declined or time ran out. Start the payment again, possibly with another card.
"SumUp: Zahlung abgebrochen." (payment cancelled)	The till cancelled the payment. The process is ended on the Solo; restart the payment if needed.
Amount appears on the wrong Solo	The workstation or device is assigned another terminal. Correct it under Operations → Workstations → EC-Terminal or in the till settings, field Terminal.
Yellow warning icon: "Reader-ID auch an Terminal … hinterlegt"	Two terminals share one reader ID. Pair one of them again with its own Solo.
Status is green but without battery or firmware details	The Solo has firmware older than 3.3.39.0. The payment works; only the extra details are missing. Update the Solo firmware.

Security

DiKAS stores the secret API key encrypted. Do not pass credentials on by e-mail or messenger and revoke the key in the SumUp account if you suspect it was lost.

Next Step¶

→ Payment methods and card payment – flow at the till, voids and credits → Hardware → Card Terminals – all card payment solutions at a glance