MLLP Transmission Mode
This transmission mode implements the Minimal Lower Layer Protocol (MLLP) specified by HL7, and is often used when transmitting HL7 v2.x messages. There are two versions of MLLP, v1 and v2. The first version is similar to the Basic TCP Transmission Mode in that it only specifies sequences for the start/end message bytes.
The second version builds on the first with "reliable delivery assurance", by having each system send a protocol-level ACK or NAK immediately after every received frame.
By default only MLLPv1 is enabled, as it is the most common use-case.
| Item | Name | Default Value | Description |
|---|---|---|---|
| A | Start of Message Bytes | 0x0B <VT>) | The MLLP Start Block bytes before the beginning of the actual message. Only valid hexadecimal characters (0-9, A-F) are allowed. |
| B | End of Message Bytes | 0x1C0D (<FS><CR>) | The MLLP End Data/Block bytes after the end of the actual message. Only valid hexadecimal characters (0-9, A-F) are allowed. |
| C | Use MLLPv2 | No | Select Yes to use the MLLPv2 bi-directional transport layer, which includes reliable delivery assurance as per the HL7 specifications. |
| D | Commit ACK Bytes | 0x06 (<ACK>) | The MLLPv2 Affirmative Commit Acknowledgement bytes to expect after successfully sending a message, and to send after successfully receiving a message. Only valid hexadecimal characters (0-9, A-F) are allowed. |
| E | Commit NACK Bytes | 0x15 (<NAK>) | The MLLPv2 Negative Commit Acknowledgement bytes to expect after unsuccessfully sending a message, and to send after unsuccessfully receiving a message. Only valid hexadecimal characters (0-9, A-F) are allowed. |
| F | Max Retry Count | 2 | The maximum number of time to retry unsuccessful dispatches before giving up and logging an error. |