About this MLLP Wrapper
HL7 v2 messages sent over plain TCP are commonly framed with Minimal Lower Layer Protocol (MLLP) characters so the receiver can detect where a message starts and ends. This wrapper helps you visualize that frame and generate a matching hex representation for testing tools or debugging notes.
Who this calculator is for
- Interface engineers testing HL7 over raw TCP or documenting message framing requirements.
- Developers who need to see the MLLP envelope around a sample message before using socket tools.
- Anyone learning what `<VT>...<FS><CR>` means in an HL7 transport discussion.
When to use it
- Use it when you need a quick visual or hex representation of an MLLP-framed HL7 message.
- Use it while troubleshooting why a TCP receiver is not recognizing message boundaries.
- Use it to document the framing bytes expected by a test harness, integration engine, or simulator.
How to use this calculator
- Paste your HL7 Message into the input box.
- The tool generates the Visual Representation (showing tags like <VT>).
- It also generates the Hex String which you can copy into a hex editor or socket testing tool.
Key assumptions
- This tool wraps the text you provide with the conventional MLLP start and end bytes only; it does not open sockets or transmit the message itself.
- The hex output represents the current browser string content byte-by-byte and is intended for inspection or manual testing, not as a full transport simulator.
- Local implementations can add additional connection rules such as keepalive behavior, TLS, retries, or site-specific acknowledgement expectations, which are outside this wrapper.
Accuracy and testing
Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.
How this calculator works
The MLLP standard wraps the message data block as follows:
`<VT> Data <FS> <CR>`
* <VT> (Vertical Tab): ASCII 11 (0x0B). Signals start of message.
* <FS> (File Separator): ASCII 28 (0x1C). Signals end of data.
* <CR> (Carriage Return): ASCII 13 (0x0D). Signals end of block.
Inputs explained
HL7 Message
The raw pipe-delimited message string.
Understanding your results
The visual output shows where framing bytes are added, while the hex output gives you a copyable representation for documentation and manual testing workflows.
Key Features
- Hexadecimal Output
- Visual Framing Tags
- Instant Wrapping
Tips & Best Practices
- Most interface engines (Mirth, Cloverleaf) handle MLLP automatically, but this tool is useful for debugging raw socket connections.
- Ensure your message itself ends with a Carriage Return (0x0D) before the MLLP footer is added.
Glossary of Terms
- MLLP
- Minimal Lower Layer Protocol. The standard for framing HL7 messages over TCP/IP.
- Socket
- One endpoint of a two-way communication link between two programs running on the network.