How to Export RDML Files From Bio-Rad CFX Maestro

Exporting an RDML file from Bio-Rad's CFX Maestro software takes about four clicks, but the option is buried in a place you wouldn't expect if you're used to a normal "Export" menu. In CFX Maestro, you don't export to RDML — you save to RDML. Go to File → Save As, then change the file type dropdown from the default .pcrd to .rdml. That's it. The resulting file contains your raw fluorescence data, well setup, and Cq values in a standardized format that any RDML-compatible analysis tool can read.

If you've been poking around in the Export menus looking for an RDML option and coming up empty, you're not alone. The Export dialogs in CFX Maestro are designed for CSV/Excel/PDF outputs — reports, essentially. RDML is treated as an alternate save format, not an export. This distinction trips up a surprising number of people, so don't feel bad about it.

Step-by-Step: CFX Maestro 2.0 (and 2.3+)

Here's the exact workflow, assuming you already have a completed run open:

1. Open your .pcrd data file in CFX Maestro. If you just finished a run, it's already open.
2. Go to File → Save As (not File → Export).
3. In the "Save as type" dropdown at the bottom of the dialog, select RDML Files (*.rdml).
4. Choose your save location, name the file, and click Save.

A few things to watch for:

• You need to have your well setup configured before saving. The RDML file will include whatever sample names, target names, and sample types (unknown, standard, NTC) you've assigned in the plate setup. If you haven't filled those in, the RDML will still export, but it'll contain generic well identifiers with no meaningful annotation. Any downstream tool will then have no idea which wells are your GOI, which are your reference gene, or which are controls.
• Biological group assignments carry over. If you've used CFX Maestro's grouping features to define biological replicates, that information is encoded in the RDML file. This is useful if your analysis tool supports it.
• Melt curve data is included. If your protocol had a melt step, the RDML will contain the melt curve fluorescence data alongside the amplification data. You don't need to export these separately.

CFX Maestro 1.1 (Legacy)

The process is essentially the same in CFX Maestro 1.1, but the interface looks slightly different. The save dialog still has the file type dropdown, and RDML is still an option there. One difference: CFX Maestro 1.1 exports RDML v1.1 files by default, while CFX Maestro 2.0+ can produce RDML v1.3 or later. In practice, this rarely causes compatibility issues, but if a downstream tool complains about the file version, this is probably why.

If you're still running the truly old CFX Manager software (pre-Maestro), the RDML export is in the same place — File → Save As — but the format option may be labeled slightly differently. Bio-Rad has been consistent about this across software generations, which is one of the few nice things about dealing with instrument vendor software.

What's Actually Inside the RDML File

An RDML file is a zipped XML archive (you can rename it to .zip and unpack it if you're curious). For a typical CFX96 run, it contains:

• Raw fluorescence readings for every cycle, every well, every channel. This is the actual curve data, not just the derived Cq values.
• Cq/Ct values as calculated by CFX Maestro using whatever threshold or regression method you had selected.
• Plate setup information: sample names, target/detector names, sample types, dye assignments.
• Thermal cycling protocol: temperatures, hold times, cycle counts.
• Melt curve data (if applicable): fluorescence vs. temperature readings.

This is substantially more information than you get from a CSV export, which typically gives you just a flat table of Cq values. The raw fluorescence data in the RDML is what allows third-party tools to recalculate Cq values using their own algorithms — which can matter if you want to apply a consistent baseline correction method across data from different instrument platforms.

Common Issues and How to Fix Them

"The RDML option doesn't appear in my Save As dropdown." This usually means you're running an older version of CFX Maestro that needs an update, or you have a run file open that was created with an incompatible protocol type. Updating to the latest CFX Maestro version (check Bio-Rad's software downloads page) almost always resolves this.

"My RDML file is 0 KB or won't open in other software." I've seen this happen when the run was aborted mid-protocol or when the .pcrd file is corrupted. Try reopening the original .pcrd file, confirming the data looks normal in CFX Maestro's amplification chart, and re-saving. If the .pcrd itself is corrupt, you may need to recover from the instrument's raw data directory (typically C:\Bio-Rad\CFX\Data or similar, depending on your setup).

"Sample names and targets are missing in the RDML." Go back to your plate setup in CFX Maestro and make sure you've actually assigned sample names and target names to your wells. A common workflow mistake: you set up the plate layout on the instrument touchscreen before the run but didn't replicate it in the software. CFX Maestro sometimes doesn't auto-populate from the instrument — you have to enter or import the layout in the software's plate editor. Once the plate setup is complete, re-save as RDML.

"I need to batch-export RDML from multiple runs." CFX Maestro doesn't have a built-in batch RDML export. Each .pcrd file needs to be opened and saved individually. If you're dealing with dozens of run files, the fastest approach is usually to keep all your .pcrd files organized in one folder and work through them sequentially. It's tedious, but it takes about 15 seconds per file once you're in a rhythm.

Why Bother With RDML Instead of CSV?

Fair question. If all you need is a table of Cq values to paste into a spreadsheet, CSV is fine. But RDML gives you a few real advantages:

• Reproducibility. The raw fluorescence data travels with the file, so anyone reanalyzing your data can verify or recalculate Cq values independently. Reviewers and collaborators increasingly expect this.
• Cross-platform compatibility. If your lab has both a CFX96 and a QuantStudio, RDML is the one format both can produce, making it easier to analyze data from mixed-instrument experiments in a single pipeline.
• Richer metadata. Sample types, replicate groupings, and protocol details are embedded in the file. A CSV gives you numbers; an RDML gives you context.
• Standardization. RDML is an open standard maintained by the RDML consortium (Lefever et al., 2009). It's not going anywhere, and it's not locked to one vendor's ecosystem.

For what it's worth, if you're moving your data into VoilaPCR, RDML is the preferred import format — it pulls in your plate layout, targets, and sample groupings automatically so you don't have to re-enter them manually.

Quick Reference

That's the whole process. The hardest part is knowing the option exists under Save As instead of Export — once you know that, you'll never spend ten minutes digging through menus again.