SAP ECC and Plaid integration

What moves between them

The primary flow runs from SAP ECC into Plaid. ml-connector polls SAP's payment registers and vendor master data, builds payment detail rows, and sends ACH transfer requests to Plaid for processing. A secondary read flow brings Plaid's transaction and balance data back into SAP: account balances sync to SAP's cash position module, and transaction statements sync to the cash reconciliation worklist daily so variance between ledger and bank is surfaced immediately. References like bank account numbers and vendor accounts are mapped between the two systems during initial setup.

How ml-connector handles it

ml-connector deploys an on-premises agent that runs RFC/BAPI calls against SAP ECC's NCo library (or JCo). For payment runs, it polls BAPI_ACC_DOCUMENT_POST records from the payment register, extracts bank account and amount fields, and submits ACH Transfer requests to Plaid using the vendor's bank details stored in SAP's vendor master. On the inbound side, it consumes Plaid webhooks for transaction SYNC_UPDATES_AVAILABLE events, verifies JWT signatures using Plaid's public key and the SHA-256 body hash, and posts the transactions into SAP's bank reconciliation module via BAPI_ACC_DOCUMENT_POST with a REF_DOC_NO matching the Plaid transaction ID to prevent duplicates on retry. Vendor disbursement lines are matched to SAP cost centers and GL accounts so payments post to the correct ledger buckets. Both systems' rate limits are respected: RFC calls are throttled to avoid SYSTEM_FAILURE exceptions, and Plaid transfer requests include idempotency keys scoped to 48 hours. Every transaction carries an audit trail with the original SAP document number and Plaid transfer ID, and transfers can be replayed if a downstream reconciliation step fails.

A real-world example

A mid-sized manufacturing company runs SAP ECC for procurement and finance, with accounts payable using a three-day payment cycle to approve invoices, consolidate vendor disbursements, and send them to the bank. Before the integration, the AP team exported payment registers from SAP as tab-delimited files, manually verified bank account routing numbers in a spreadsheet, then logged into the bank portal to initiate transfers, manually typing recipient account data. Reconciliation happened a week later via bank statement download. With SAP ECC and Plaid connected, the payment run from SAP feeds directly to the bank via ACH initiation in Plaid, and transaction statements flow back into SAP daily for instant reconciliation. The AP team now spends 30 minutes on payment day reviewing the confirmation batch, not three hours on data entry and bank portal clicks.

What you can do

• •Poll SAP ECC payment registers and initiate ACH transfers to Plaid for vendor disbursement.
• •Sync Plaid transaction statements back into SAP's cash reconciliation module daily.
• •Match vendor payment details to SAP cost centers and GL accounts so disbursements post to the correct ledger accounts.
• •Authenticate SAP ECC via RFC/BAPI with an on-premises agent and Plaid via client_id and secret with JWT webhook signature verification.
• •Prevent duplicate ACH transfers and reconciliation entries using idempotency keys and transaction ID mapping across the full payment-to-reconciliation cycle.

Questions

What is the direction of data flow between SAP ECC and Plaid?

The primary flow is SAP ECC to Plaid: payment registers from SAP are sent to Plaid for ACH initiation. The secondary flow is Plaid to SAP: transaction statements and account balances from Plaid are posted back into SAP's cash reconciliation module daily. GL postings (accounting entries) are never initiated by Plaid; Plaid is read-mostly for account data and read-write for transfer initiation.

Does SAP ECC's on-premises requirement affect the integration?

Yes. SAP ECC runs on-premises and does not expose RFC/BAPI via the public cloud, so ml-connector requires an integration agent deployed on the customer's network with SAP .NET Connector or Java Connector installed. The agent sits behind the corporate firewall and makes RFC calls to the SAP system, while Plaid connectivity happens from the agent outbound via HTTPS to production.plaid.com. The agent is managed by ml-connector and requires no manual RFC configuration on the SAP Basis side beyond the basic user credential setup.

How does ml-connector handle Plaid webhook signatures and prevent duplicate transactions?

Plaid delivers webhooks with JWT signatures (ES256) and includes the SHA-256 hash of the raw request body. ml-connector verifies the signature using Plaid's public JWK key and rejects any webhook that does not pass signature verification or whose iat claim is more than 5 minutes old. For duplicate prevention, each Plaid transaction is mapped to a REF_DOC_NO in SAP, and ml-connector checks SAP's reconciliation table before posting; if the transaction ID has already been posted, the entry is skipped. Transfers to Plaid include idempotency keys that expire after 48 hours, so a retry of the same payment does not result in a duplicate ACH submission.