GS805 guides · Nayax · written by an operator who runs one
GS805 and Nayax: how payments, reports and failed vends actually work
Most GS805 protein shake machines sold in Europe come with a Nayax card reader, and so does ours. This page answers what owners ask: does Nayax work with the GS805, how the payment and the drink are connected, what happens to the money when the machine fails to make the drink, what Nayax Core can report and what it cannot, what the Nayax API is for, and where VendCaptain fits.
Does Nayax work with the GS805?
Yes. The GS805 takes a cashless card reader on an MDB bus (Multi-Drop Bus, the vending industry's standard for payment devices), and Nayax's MDB readers are what European suppliers fit as standard. Our machine has sold with one since it opened in May 2026 under the factory app, and VendCaptain drives the same reader in its tests on that machine.
Three facts follow from the MDB design, and they explain everything else on this page:
- The reader does the card work on its ownIt talks to Nayax over its own modem, processes the card, and tells the machine one thing: approved or declined. The machine, and any software on its screen, never sees card data.
- Whichever app sells drives the readerThe factory app asks the reader for a payment, and so does VendCaptain's app when it is the seller. Two apps must never drive the reader at once: that is how a customer gets charged twice or not at all.
- Nayax keeps the record of the moneyEvery card transaction lands in Nayax Core, Nayax's own portal: authorisation, settlement, refunds, card brand and last four digits. The machine's software keeps the record of the drink. Neither knows the other.
- Other MDB terminals fit the same wayBecause the connection is MDB, a bank's unattended payment terminal or another provider's reader can take Nayax's place. VendCaptain connects any MDB terminal to Run on request; see GS805 integrations.
How the payment and the drink are connected
- 1. The customer choosesThe screen app shows the menu and asks the reader for the price of the drink.
- 2. The reader approvesThe customer taps. The reader processes the card and answers approved or declined. The money is taken at this moment.
- 3. The machine makes the drinkThe screen app tells the machine board to drop the cup, dose the powder and water, and mix. Only now does anyone find out whether the machine can.
The one fact that matters most
On a GS805 with a Nayax reader, the charge is captured when the tap is approved, before the drink is made. We verified this on our own machine with real transactions in July 2026. It is the reason "paid, no drink" is the most common complaint about these machines, and the reason the next section exists.
What happens after a failed vend
The reader has already taken the money. Whether the customer gets it back depends entirely on the software on the screen, because only that software can tell the reader to reverse the charge. What we observed on our machine, reading our own Nayax Core transactions:
- The older factory app
- Never gave money back on a cancel after approval. Six sessions that were approved and then cancelled, in June 2026, all settled at full price, and the operator refunded them by hand in Nayax Core hours later.
- The updated factory app
- Sends a reversal to the reader when the vend fails. Nayax logs it as event 811, "product failed to be dispensed", and the transaction closes at 0.00 about 45 seconds after the tap. We have two such rows on our account. If your machines run an older app, failed vends may be charged and never refunded, and nothing tells you.
- VendCaptain's app (Run)
- Marks the sale failed the moment the machine cannot make the drink, tells the customer on the screen, and lists the payment for you with what is owed. The refund itself is made in your Nayax account: VendCaptain never moves money.
- VendCaptain on any app (Connect)
- Pairs every card transaction with the drink on the same machine, at the same price, within a few minutes, and gives each failed vend one state: refunded by the machine's software, reversed at Nayax, refunded at Nayax by a person, still charged, or not found. What is still charged is a list you can work through.
How to see it yourself in Nayax Core. Open the transactions for one machine and look at the status column. On our account the statuses read like this: settled; settled, then refunded by a person; reversed by the machine; declined at authorisation; voided before capture. A machine whose failed vends never show "reversed by the machine" is running software that does not reverse. One operator's 25 machines, in their first day on VendCaptain, showed 150 card payments that took the money and made no drink, 462 euros, only 8 of them refunded. It was all in their Nayax data.
GS805 payment reporting: what Nayax Core gives you, and what it cannot
- What Nayax Core has
- Every card transaction with its time, machine, amount authorised, amount settled, refund amount, card brand and last four digits, and for Nayax's own wallet a payment token. Reports can be exported; the one VendCaptain reads is the Dynamic Transactions Monitor.
- What Nayax Core does not have
- Which drink was sold. The GS805 does not pass product information to the reader, so the product on a Nayax row usually reads "Unknown" followed by the price. Nor does it know whether the drink was made. Both facts live in the machine's software, on the other side.
- What the factory cloud has
- Each sale with its drink, price, time, machine, and whether the machine reported it made. No card, no settlement, no refund made at Nayax.
- What only the two together can tell you
- A charge with no drink and no refund. A drink that was made but never charged. A refund already made at Nayax for a vend the factory cloud still calls failed. A card that comes back every week. VendCaptain joins the two records by machine, amount and time, in the machine's local time, and persists the match. The pages that show the join are on GS805 remote monitoring.
A trap in the export
The Dynamic Transactions Monitor report has a Results setting that defaults to 200 rows. It silently cuts the report short: everything past the limit never reaches the file. Set it above your transaction count before you export, and check the row counter at the bottom against the file. Export in one language and stay with it: Nayax translates both the column headers and some values, and mixing languages lists the same payment method twice.
The Nayax API and the GS805
Searches for a "GS805 Nayax API" usually want one of three things, and they have three different answers.
- Sales per drink, by program
- That is not Nayax data. It lives in the machine's software: the factory cloud on a standard GS805, VendCaptain's cloud on Run. The maker publishes no API for its cloud that we know of; VendCaptain Connect reads it with your own account.
- Card transactions, by program
- Nayax publishes the Lynx API for its customers, with a role Nayax grants per account. Nayax can also push each transaction as a message to an Amazon SQS queue you own. VendCaptain uses the push and the report export, not Lynx, and does not resell or configure Nayax services.
- The two joined
- No API gives you this, because no single system holds both halves. It is what VendCaptain does every hour, from the factory cloud and from your Nayax export or push. The result is the list of failed payments, the repeat-buyer analytics, and what each price did.
An owner's checklist, before anything is installed
- Export last month from Nayax Core for one machine, with Results set above your row count, and count the rows that settled at full price with no refund and no "reversed" status. Compare the count with the drinks that machine reported made in the factory cloud for the same days.
- Find out which app version your machines run. If no transaction on any machine ever shows a machine-side reversal, failed vends are staying charged.
- Decide your refund policy and who checks for charges with no drink, and how often. Most operators have never done it, because nothing shows them the list.
- Keep one export language. Pick English or Spanish in Nayax Core and never switch.
- Write down which reader each machine has. Ask your supplier for the Nayax model and firmware; the behaviours on this page were observed on ours and may differ on yours. The rest of the machine's setup is in the owner's guide.
Every item on this list is what the first day of a VendCaptain pilot does for you, from your own Nayax export and the account you already have. Start a free pilot or read the GS805 troubleshooting guide for the other things that go wrong.
Questions owners ask about Nayax on the GS805
Does the GS805 need the factory app for Nayax to work?
No. The reader works with whichever app drives it over MDB. The factory app does, and so does VendCaptain's app on Run. The reader does not know or care which one.
Can VendCaptain refund a customer at Nayax?
No. VendCaptain never moves money. It tells you which payments made no drink and what is still owed; you make the refund in Nayax Core, and VendCaptain marks it refunded on the next pass.
Why does my Nayax transaction say "Unknown" and a price instead of the drink?
Because the GS805 does not pass product information to the reader. The drink is only in the machine's software. VendCaptain fills it in by pairing the transaction with the sale on the same machine at the same price within a few minutes.
What is Nayax event 811?
Nayax's label for "product failed to be dispensed": the machine's software told the reader to reverse a charge because the drink was not made. On a GS805 you only see it if the app on the screen sends that reversal. The older factory app did not.
Do I need the Nayax Lynx API to use VendCaptain?
No. Every pilot starts with the report you export from Nayax Core. If you want it automatic, Nayax can push each transaction to a queue you own, which we set up with you.
Does VendCaptain see card numbers?
No. Card brand and last four digits only, as Nayax's own export carries them. That is enough to recognise a returning customer and nothing more.
Can I use a reader that is not Nayax?
On Connect, any reader: VendCaptain reads the machine's sales, not the reader. On Run, VendCaptain comes with Nayax and connects any MDB payment terminal on request; see GS805 integrations.
More GS805 guides
- GS805 integrationsConnect, Run, where Nayax fits, and which APIs and SDKs are not offered.
- GS805 troubleshootingPaid but no drink, idle machines, run-outs, the waste bucket, a frozen screen: what each is and what to do.
- GS805 remote monitoringFactory telemetry against VendCaptain Connect and Run, and which data exists at all.
- GS805 owner's guideSoftware, payments, setup, calibration and cleaning, with the official manuals linked.
- GS805 loyalty and promotionsDiscount windows and codes in the factory software, and the stamp card and happy hours VendCaptain adds.
- Running a GS805 in a gymOne machine in a Madrid studio since May 2026: what we found, and what changes when our software becomes the seller.
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Daniel Escobar escobar@vendcaptain.com +34 623 345 790 Email, WhatsApp or phone