Assuming you have applied the balance of the Merchant Card to the Smart Transaction, and the missing_sum was 0 (zero). You can pay the full amount redeeming your card balance now.

You can execute the payment calling the endpoint POST /api/v2/Smart/Transactions/{id}/start/loyalty:

Request
POST /api/v2/Smart/Transactions/STX_KJXJDUN542NR3WMRHRVU5WWM6ZQEA2/start/loyalty HTTP/1.1
Host: connect-testing.secuconnect.com
Authenticate: Bearer qb56tjj1bcvo9n2nj4u38k84lo
Accept: application/json

If everything is fine, the API responds with 200 OK, and the Smart Transaction will change to status ok (line 25):

Response
HTTP/1.1 200 OK
Content-Type: application/json
...
 
{
"object": "smart.transactions",
"id": "STX_KJXJDUN542NR3WMRHRVU5WWM6ZQEA2",
"merchant": {
"object": "general.merchants",
"id": "MRC_35SZ3R5GGQQP4T0U2T5GFAN9P6C4PG",
"companyname": "John's Bakery"
},
"device_source": {
"object": "smart.devices",
"id": "SDV_2YJDXYESB2YBHECVB5GQGSYPNM8UA6"
},
"transactions": [
{
"object": "loyalty.transactions",
"id": "LTX_YBYPUETZ2HQXURG9XU0M5H4KGWW0NH"
}
],
"created": "2020-09-17T09:18:14+02:00",
"updated": "2020-09-17T09:43:59+02:00",
"status": "ok",
"merchantRef": null,
"transactionRef": null,
"intent": null,
"basket": {
"products": [
{
"id": 1,
"parent": null,
"articleNumber": "30037",
"ean": "",
"desc": "Sandwich Romano",
"quantity": 1,
"priceOne": 349,
"tax": 7,
"group": [],
"serialNumber": null,
"item_type": "article",
"reference_id": null,
"contract_id": null,
"sum": null
},
{
"id": 2,
"parent": null,
"articleNumber": "30200",
"ean": "",
"desc": "Fruit salad, small bowl",
"quantity": 1,
"priceOne": 249,
"tax": 7,
"group": [],
"serialNumber": null,
"item_type": "article",
"reference_id": null,
"contract_id": null,
"sum": null
},
{
"id": 3,
"parent": null,
"articleNumber": "51",
"ean": "4999012345678",
"desc": "Water, mildly sprinkling, 0.25 ltr.",
"quantity": 2,
"priceOne": 99,
"tax": 19,
"group": [],
"serialNumber": null,
"item_type": "article",
"reference_id": null,
"contract_id": null,
"sum": null
}
],
"texts": [],
"type": "default"
},
"receipt": [
{
"type": "separator",
"value": {
"caption": "Kundenkarte"
}
},
{
"type": "name-value",
"value": {
"name": "Kartennummer:",
"value": "9276004429942845",
"decoration": []
}
},
{
"type": "name-value",
"value": {
"name": "TA Code:",
"value": "29008410",
"decoration": []
}
},
{
"type": "space"
},
{
"type": "textline",
"value": {
"text": "Zahlung über:",
"decoration": []
}
},
{
"type": "textline",
"value": {
"text": "7,96 EUR",
"decoration": [
"important"
]
}
},
{
"type": "space"
},
{
"type": "textline",
"value": {
"text": "Umsatz erfasst:",
"decoration": []
}
},
{
"type": "textline",
"value": {
"text": "7,96 EUR",
"decoration": [
"important"
]
}
},
{
"type": "space"
},
{
"type": "textline",
"value": {
"text": "Aktuelles Guthaben",
"decoration": []
}
},
{
"type": "textline",
"value": {
"text": "2,51 EUR",
"decoration": [
"important"
]
}
}
],
"basket_info": {
"sum": 249,
"currency": "EUR",
"gratuity": null,
"missing_sum": 0
},
"idents": [
{
"object": "smart.idents",
"id": "smi_1",
"prefix": "9276",
"name": "secucard Kundenkarte",
"type": "card",
"value": "9276004429942845",
"valid": true,
"merchantcard": {
"object": "loyalty.merchantcards",
"id": "MCD_2RXTNXPRM2YG9922UMBHHAEWEGN6AJ",
"merchant": {
"object": "general.merchants",
"id": "MRC_35SZ3R5GGQQP4T0U2T5GFAN9P6C4PG"
},
"created_for_merchant": {
"object": "general.merchants",
"id": "MRC_35SZ3R5GGQQP4T0U2T5GFAN9P6C4PG"
},
"card": {
"object": "loyalty.cards",
"id": "CRD_2U7MTNAMM3PMBPAB50C9G2AEHA9GPJ",
"cardnumber": "9276004429942845",
"created": "2015-09-28T16:01:20+02:00"
},
"cardgroup": {
"object": "loyalty.cardgroups",
"id": "CRG_2BESGJNETJJRZVVYS8R7JWGVWK4PRZ",
"display_name": "Geschenkgutschein",
"display_name_raw": "Geschenkgutschein",
"stock_warn_limit": 0,
"picture": "https://connect.secucard.com/ds_g/8e79737df1e2513db48908b342c3cc436edf501a"
},
"created_for_store": {
"object": "general.stores",
"id": "STO_2ZCZRU9V6U8QA7B49K94667UP6C4PJ"
},
"customer": {
"object": "loyalty.customers",
"id": "CUS_2YBREKK0A2MNAXJ752TSDD9DH3PKAJ",
"contact": {
"name": "Max Mustermann",
"forename": "Max",
"surname": "Mustermann",
"dob": "2018-02-14T00:00:00+00:00"
},
"created": "2018-05-03T10:14:06+02:00",
"consent_for_communication": true
},
"is_base_card": true,
"points": 0,
"cash_balance": 251,
"bonus_balance": 0,
"balance": 251,
"last_usage": "2020-03-17T07:22:36+01:00",
"last_charge": "2019-12-10T12:56:08+01:00",
"stock_status": "active",
"lock_status": "unlocked",
"passcode": 0,
"expiry_date": null
},
"customer": {
"object": "loyalty.customers",
"id": "CUS_2YBREKK0A2MNAXJ752TSDD9DH3PKAJ",
"contact": {
"name": "max Mustermann",
"forename": "max",
"surname": "Mustermann",
"dob": "2018-02-14T00:00:00+00:00"
},
"created": "2018-05-03T10:14:06+02:00",
"consent_for_communication": true
}
}
],
"payment_method": "loyalty",
"trans_id": "29008411",
"is_demo": false,
"application_context": {
"locks": {
"customer": false
},
"return_urls": null,
"iframe_opts": null
},
"checkout_links": null,
"payment_links": null
}

If you take a closer look you will see:

  • a reference to a Loyalty Transaction in the field transactions;
  • a number of receipt lines in receipt.

There is another section that explains how to print or display the receipt.