HL71 input → 2 outputs

HL7 Out

Sends an HL7 v2 message to a hospital's HL7 listener over a dedicated VPC connection using MLLP.

Details

Opens a short-lived MLLP socket to the hospital's HL7 listener (host and port configured on the connection's outbound settings), sends the message, waits for the ACK, then closes the connection.

The destination is read from the connection's HL7 → Outbound settings — not from the message. Configure the hospital's HL7 listener IP and port in the connection before using this node.

Inputs

payload string: Raw HL7 v2 message. Segment separator can be \r, \n, or \r\n — the node normalises to \r before sending. MLLP framing (0x0B … 0x1C 0x0D) is added automatically.
payload string[]: Array of raw segment strings (e.g. ["MSH|...", "PID|...", "PV1|..."]). Segments are joined with \r before sending. Easiest format to build manually with an Inject node (set type to JSON).
payload.segments string[]: Structured object from an HL7 Parser node — { segments: ["MSH|...", ...] }. Segments are joined with \r.
payload.raw string: Object with a .raw string field — { raw: "MSH|..." }.

Outputs

Output 1 — ACK received (including AE/AR — these are application-level responses, not errors):

payload.ackCode string: ACK code from hospital: AA (accept), AE (error), AR (reject).
payload.ackMessage string: Raw ACK HL7 message returned by the hospital.
payload.durationMs number: Round-trip time in milliseconds.
payload.host string: Hostname or IP that was connected to.
payload.port number: Port that was connected to.
hl7.ackCode string: Shortcut: ACK code (AA / AE / AR).

Output 2 — Network / transport error:

payload.error string: Error description (connection refused, timeout, socket closed before ACK, etc.).
payload.durationMs number: Time elapsed before the error occurred.

Typical Flow

┌────────────┐   ┌──────────┐   ┌─────────┐
│  Function  │──▶│  HL7 Out │──▶│  Debug  │  (Output 1: ACK)
│ (build msg)│   └──────────┘
│            │         │
│            │         └──────▶│  Error  │  (Output 2: network error)
└────────────┘                 └─────────┘

ACK Handling

A non-AA ACK code (AE / AR) is routed to Output 1 — not Output 2. This lets you inspect the hospital's application-level rejection in the flow. Only true network failures (connection refused, timeout, socket closed early) go to Output 2.

Best Practices

Validate and build the HL7 message string in a Function node before wiring here
Always handle Output 2 — network errors are common during maintenance windows
Check payload.ackCode on Output 1 to distinguish AA vs AE/AR responses
Log the payload.durationMs to monitor outbound MLLP latency

┌────────────┐ ┌──────────┐ ┌─────────┐ │ Function │──▶│ HL7 Out │──▶│ Debug │ (Output 1: ACK) │ (build msg)│ └──────────┘ │ │ │ │ │ └──────▶│ Error │ (Output 2: network error) └────────────┘ └─────────┘