Analyzer interfacing explained: HL7 vs ASTM vs serial

Every analyzer in your lab already produces its results as data. Interfacing means capturing that data into your LIS instead of reading the screen and typing. For a 150-sample lab it removes more than an hour of typing a day and, for interfaced results, the transcription errors that come with it. This guide explains the three ways analyzers talk, which one your machine uses, and how to get it connected.

The three languages analyzers speak

HL7 version 2 over TCP/IP

The hospital standard. The LIS sends an ORM (order) message and the analyzer replies with an ORU (result) message, each a set of pipe-separated segments: MSH for the header, PID for the patient, OBR for the order, OBX for each result with value, unit, reference range and an abnormal flag. It travels over the lab's ordinary network cable. Modern Sysmex XN, Mindray BC-5150 and BS-240, Roche cobas and Beckman AU units use it. HL7 is fast and carries the richest data.

ASTM E1394 (now CLSI LIS2-A2)

The older laboratory standard that most analyzers still implement. Records are lines beginning with a letter: H header, P patient, O order, R result, L terminator, wrapped in a low-level handshake (ENQ, ACK, EOT) defined by ASTM E1381. It runs over TCP or over an RS-232 serial cable. Erba EM 200, Horiba Micros, Transasia, Agappe and many immunoassay analyzers use it. Correctly configured, it is as reliable as HL7; the usual failures are framing and checksum settings, not the protocol.

Serial text capture

Semi-automatic analyzers (a Chem 7, an electrolyte unit, many HbA1c units) do not know which sample they are running. They print a result through an RS-232 port. The LIS connector captures that printed stream, and the technician matches it to a sample on screen. It is the least elegant method and still removes all retyping.

Bidirectional or result-only?

Result-only (unidirectional): the technician scans or types the sample ID on the analyzer; the analyzer sends results back; the LIS matches the ID. Almost every 3-part cell counter works this way. Bidirectional: when the analyzer reads the barcode it asks the LIS what tests are ordered and runs exactly those. This matters most on random-access biochemistry analyzers, where typing the worklist on the machine takes as long as typing the results. Fully automated analyzers support bidirectional; if yours does, use it. The one risk is barcode mismatch: the symbology (usually Code 128) and the ID length on the tube label must match what the analyzer's reader is set to.

What hardware is needed

• LAN analyzers: nothing beyond a network cable. The analyzer and the connector PC must be on the same network, and the analyzer's LIS settings get the connector's IP and port.
• Serial analyzers: a USB-to-serial adapter (about ₹600 for a reliable FTDI-chip one) or a serial-to-LAN converter (₹2,500 to ₹4,000) if the PC is in another room. Some units need a null-modem cable. Baud rate, data bits, parity and stop bits (commonly 9600, 8, N, 1) must match on both sides.
• A connector PC: any Windows machine already in the lab. Disable sleep. The connector should run as a service so it survives a reboot and a logged-out screen.

Offline behaviour

Cloud LIS products differ most here. The right design keeps the connector local: it receives from the analyzer whether or not the internet is up, stores results on the PC, and syncs when the connection returns. If a vendor's interfacing stops the moment the broadband drops, the lab will go back to typing on exactly the days it is busiest. Ask to see the queue.

Mapping: the one-time work

Each analyzer sends its own parameter codes: HGB, WBC, PLT on a cell counter; GLU, CREA, ALT on a chemistry analyzer. The connector maps each code to a test in your test master once. Units matter: a counter may send platelets as 10^3/µL while your report shows lakh/µL. Decide which side applies the reference ranges. Our recommendation is the LIS, so there is one source of truth for H/L flags on reports and in the audit trail, and the analyzer's own limits are set wide.

Verification before go-live

1. Run three samples with known results (a QC material and two patients from the morning).
2. Check each landed on the correct sample ID with the correct unit, decimal places and flag.
3. Rerun one sample and confirm the LIS shows both results side by side rather than overwriting.
4. Unplug the internet, run a sample, reconnect, confirm it syncs.

Keep the thermal printouts for the first week. After that most labs switch them off.

What interfacing should cost

Many Indian LIS vendors still treat interfacing as a premium: as of October 2026, CrelioHealth's India plans cap the number of analyzers per tier, and Flabs includes machine interfacing only in its top plan. Others quote a fee per connection, so ask. There is no technical reason for a per-machine fee once the connector exists. PathLab Software includes interfacing for every analyzer in the Pro and Chain plans; our analyzer page has a compatibility matrix with honest testing status (simulator-tested, validated on site at go-live, on request) and per-model notes for Sysmex XN-350, Erba EM 200, Mindray BC-30 and BS-240, Horiba Micros 60 and the Transasia Chem 7.

Common problems and fixes

• Results arrive but do not match a sample: the ID was typed with a wrong digit, or the label has a prefix the analyzer strips. Use scanned IDs; use a check digit.
• Analyzer shows "host not responding": wrong IP or port, a Windows firewall rule, or the connector service stopped. Check in that order.
• ASTM checksum errors: parity or stop bits differ. Match the analyzer's printed configuration page exactly.
• Units off by a factor of 10 or 1,000: fix in the mapping, not on the report template.

Where to go next

Interfacing is one part of a complete lab management software setup; it also feeds the analyzer and reagent-lot evidence on the NABL readiness page. Check which plans include it on PathLab Software pricing, or read the step-by-step notes for the Mindray BC-30 and Sysmex XN-350.

Questions people ask

What is the difference between HL7 and ASTM for lab analyzers?

HL7 v2 is a message standard with ORM orders and ORU results, sent over the lab network and used by most modern analyzers. ASTM E1394 (CLSI LIS2-A2) is an older record-based standard that runs over TCP or RS-232 serial. Both work once framing and parameter mapping are set; with PathLab Software each analyzer is validated on site with known samples at go-live.

Can one PC run the connector for several analyzers?

Yes. One connector handles any number of LAN analyzers and as many serial ports as the PC has (USB-to-serial adapters add more). Most labs run everything from the PC beside the main cell counter.

Does interfacing work with a collection centre that has no analyzer?

The centre does not need a connector. It registers and barcodes samples; the hub's analyzers read those barcodes and results flow back to the order, which can be reported under the centre's header.

Do I need the manufacturer's engineer to enable the LIS port?

On some units (Sysmex, Roche, Beckman) the host output is behind a service menu, so the engineer enables it once. On Mindray, Erba and Horiba units the LIS settings are in the user menu and your senior technician can do it over a screen share with us.