Terminal API

The Terminal API is how your ECR talks to Aera terminals. It uses Nexo Retailer messages: your ECR sends a request, and the terminal answers with a response. Use it to take payments, refunds and gift card payments, and to close the day.

How a payment works

Open a session. Send Login when the ECR starts.
Take the payment. Send Payment. While the customer pays, the terminal sends Display messages, so you can show the status to the cashier.
Read the result. Use the Payment response. If you don't get one, ask with TransactionStatus before you charge the customer again.
Close the day. Send Reconciliation.

sequenceDiagram
    participant E as Your ECR
    participant T as Aera terminal
    E->>T: Login
    T-->>E: Login response
    E->>T: Payment
    T-->>E: Display (status for the cashier)
    T-->>E: Payment response
    Note over E,T: No response? Send TransactionStatus
    E->>T: Reconciliation (end of day)
    T-->>E: Reconciliation response

Session

Start and end the connection.

Payments

Take payments and refunds.

Payment follow-up

Cancel, undo or check a payment.

Gift cards

Load gift cards and check the balance.

End of day and checks

Close the day and check the connection.

Terminal screen and events

What the terminal shows, asks and tells you.

All messages at a glance

Message	Class	Used for
Message header	–	Header fields in every message
Login	Service	Open a session
Logout	Service	Close a session
Payment	Service	Purchase, loyalty, cashback, cash advance, cash deposit, refund
CardAcquisition	Service	Read the card before paying; identify or onboard customers
EnableService	Service	Stop after CardAcquisition
Abort	Service	Cancel a request in progress
Reversal	Service	Undo the last transaction
TransactionStatus	Service	Result of an earlier transaction
StoredValue	Service	Activate and load gift cards
BalanceInquiry	Service	Gift card balance
Reconciliation	Service	Close a period, get totals
Diagnosis	Service	Check connectivity
Display	Device	Status and result screens
PIN	Device	PIN entry controlled by the ECR
Input	Device	Customer or cashier input (onboarding, BankAxept backup)
Event	Event	Notifications from the terminal

Service messages are requests from the ECR. Device messages control the terminal's screen and keypad. Event messages come from the terminal without being asked.

Before you start

You need	Where
A connection from your ECR to the terminal	Connect your ECR
The fields every message starts with	Message header
What response codes mean	Response codes

Field tables show nesting with indented ↳ names. A field belongs to the nearest less-indented row above it.

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New to the Terminal API?
Start with the guide: Implement the payment flow.