# Encountered unsupported non-voltage units?

**URL:** <https://mne.discourse.group/t/encountered-unsupported-non-voltage-units/6998>\
**Category:** Support & Discussions\
**Tags:** eeg\
**Created:** [June 1, 2023, 9:42pm UTC](https://mne.discourse.group/t/encountered-unsupported-non-voltage-units/6998 "2023-06-01T21:42:16Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![letitiayhho](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/letitiayhho/32/2701_2.png) [@letitiayhho](https://mne.discourse.group/u/letitiayhho)\
**Post date:** [June 1, 2023, 9:42pm UTC](https://mne.discourse.group/t/encountered-unsupported-non-voltage-units/6998/1 "2023-06-01T21:42:17Z")

</div>

MNE version: 1.0.3  
Operating system: CentOS Linux 7 (Core)

write\_raw\_bids() is giving me an error and won’t write my data to BIDS format.

```python
write_raw_bids(
    raw,
    bids_path = bids_path,
    allow_preload = True, # whether to load full dataset into memory when copying
    format = 'BrainVision', # format to save to
    anonymize = dict(daysback = daysback_min), # shift dates by daysback
    overwrite = True,
)

```

The error is

```python
Writing '../data/bids/participants.tsv'...
Writing '../data/bids/participants.json'...
Writing '../data/bids/sub-6/eeg/sub-6_space-CapTrak_electrodes.tsv'...
Writing '../data/bids/sub-6/eeg/sub-6_space-CapTrak_coordsystem.json'...
Used Annotations descriptions: ['111', '112', '113', '121', '122', '123', '131', '132', '133', '211', '212', '213', '221', '222', '223', '231', '232', '233']
Writing '../data/bids/sub-6/eeg/sub-6_task-pitch_run-1_events.tsv'...
Writing '../data/bids/dataset_description.json'...
Writing '../data/bids/sub-6/eeg/sub-6_task-pitch_run-1_eeg.json'...
Writing '../data/bids/sub-6/eeg/sub-6_task-pitch_run-1_channels.tsv'...
Copying data files to sub-6_task-pitch_run-1_eeg.vhdr
/tmp/slurmd/job27623835/slurm_script:100: RuntimeWarning: Converting data files to BrainVision format
  write_raw_bids(
/home/user/.conda/envs/pitch-tracking/lib/python3.10/site-packages/pybv/io.py:394: UserWarning: Encountered unsupported non-voltage units: n/a
Note that the BrainVision format specification supports only µV.
  warn(msg)

```

Any ideas?

---

<div class="post-metadata">

**Author:** ![mainakjas](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/mainakjas/32/34_2.png) [@mainakjas](https://mne.discourse.group/u/mainakjas)\
**Post date:** [June 2, 2023, 1:32am UTC](https://mne.discourse.group/t/encountered-unsupported-non-voltage-units/6998/2 "2023-06-02T01:32:15Z")

</div>

Hi – have you tried using raw.set\_channel\_types:

[https://mne.tools/stable/generated/mne.io.Raw.html#mne.io.Raw.set\_channel\_types](https://mne.tools/stable/generated/mne.io.Raw.html#mne.io.Raw.set_channel_types)

?

Mainak