Attach files and photos
Give Centrus a photo, a PDF or a spreadsheet to read alongside your question. This guide covers which files you can attach, the paperclip, drag and drop and paste, attaching from a phone, what a sent file looks like, opening it again and who else can see it.
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On this page13 sections
- 1What attaching is for
- 2Files you can attach
- 3Attach a file from your computer
- 4Drag and drop, or paste
- 5Which AI models read which files
- 6Send a photo from your phone
- 7Check or remove files before you send
- 8What a sent message shows
- 9Open an attachment later
- 10Who can see your attachments
- 11Good things to attach
- 12Files in WhatsApp and Teams
- 13Limits and messages
What attaching is for
Attach a file when the answer depends on something Centrus has not seen: a photo of a fault code, a supplier's quote, an export from another system. The file goes with your message, Centrus reads it alongside your files in Train, and you can keep asking about it for the rest of the chat.
Start conversations with Centrus
Your personal chat history, excluding agent-generated threads.
08 Oct 07:50
John Martin
last message sent: 1 minute ago
What does this mean, and is there anything on last month's service sheet?
The display shows F28, an ignition lockout: the boiler tried to light and failed. Your September service sheet notes that the ignition electrode was worn and due for replacement, so check that first, then the gas supply and the condensate pipe.
Sources:
- • Boiler fault codes.txt
- • Riverside House boiler O&M manual.pdf
Centrus may make mistakes. Check important info.
- 1The paperclip, on the message bar, for choosing files to attach.
- 2A file waiting to go with your next message.
- 3A sent message, with the photo it carried.
- 4Centrus's answer, which read the photo and your files in Train.
An attachment belongs to the chat you sent it in. It is not added to Train, it is not searched in your other chats, and colleagues who share your tags do not see it. For a document everyone should be able to ask about, such as a manual or a price list, upload it to Train instead, as described in Upload files.
Attach in chat
The paperclip, drag and drop, or paste
- Used in
- This chat only, from the message you send it with
- Who sees it
- You, and anyone who can read this chat
- How Centrus reads it
- The whole file is given to Centrus with your message
- Files
- PDFs, spreadsheets and JPEG or PNG photos, up to 20 in a message
- Storage
- Does not count towards your Train storage
Upload to Train
Train, on the Files tab
- Used in
- Every chat that uses the file's tags
- Who sees it
- Everyone who has one of the file's tags
- How Centrus reads it
- Searched for the passages that match each question
- Files
- PDF, Word, spreadsheets, text and audio
- Storage
- Counts towards your organisation's storage
For the rest of the Chat page, including the other buttons on the message bar, see Chat in the web app.
Files you can attach
A web chat takes three kinds of file. Anything else is turned away with a message when you try to add it.
Read as a document, text, tables and all
Spreadsheets
.xlsx.xls.csv
Each worksheet becomes a table
Photos and screenshots
.jpg.jpeg.png
Looked at as a picture
- PDFs: quotes, certificates, service sheets, drawings and reports. Centrus reads the text and the layout.
- Spreadsheets (.xlsx, .xls and .csv): each worksheet is turned into a table before Centrus reads it, so keep a single heading row at the top of each sheet and avoid merged cells.
- Photos and screenshots (.jpg, .jpeg and .png): Centrus looks at the picture itself, so it can read a display, a label or a handwritten note.
Word and PowerPoint files cannot be attached in a web chat. Save the document as a PDF and attach that, or upload the Word file to Train if others will need it too.
Attach a file from your computer
- 1Open the chat the file is for, or start a new one. You can only attach files in your own chats.
- 2Click the paperclip on the message bar. Resting the pointer on it shows which files your AI model accepts.
- 3Choose one or more files and click Open. You can pick up to 20 at once.
- 4Wait for the spinner on the paperclip to stop. The files then appear above the message bar.
- 5Type your question and press Enter, or click Send.
Send me a photo of the display and I will look up the code.
Files upload one at a time, and none of them appear above the bar until the last has finished. A handful of photos takes a few seconds; a large PDF can take longer.
While the files upload
When they are ready
Wait for the spinner to stop before you send. Send is not blocked while files are uploading. If you send before the spinner stops, your message goes without the files, and they wait above the bar for your next one.
Drag and drop, or paste
Drag files from your desktop, a folder or an email straight onto the message bar. The bar turns blue while files are over it; let go and they upload as if you had used the paperclip.
John Martin
last message sent: less than a minute ago
Send the quote over and I will check each line against the 2026 rate card.
You can also paste. Copy a screenshot or an image, click in the message box and press Ctrl+V (or Cmd+V on a Mac). A pasted screenshot arrives as a PNG.
Which AI models read which files
Every model in the AI Model list reads PDFs, spreadsheets and photos. Four older reasoning models, O1, O3, O3 Mini and O4 Mini, read PDFs and spreadsheets but not photos. They are no longer offered, but a chat or organisation set to one of them before keeps it.
With one of those older models, the file picker hides photos and a dragged or pasted photo is turned away with Unsupported file type. The paperclip's tooltip shows which files the current model accepts. Your own choice of model, if you have set one, takes the place of your organisation's. To check or change it, see Choose the AI model.
Send a photo from your phone
On a phone, the message bar's tools are tucked behind a menu button at its left, with the paperclip at the bottom of the list.
CentrusJohn Martin
The boiler in the plant room has stopped. I will send you a photo of the display.
Send it over and I will look up the code in the Riverside House boiler manual.
Centrus may make mistakes. Check important info.
- 1Tap the menu button at the left of the message bar, then the paperclip.
- 2Your phone offers to take a photo, choose one from your library or pick a file. Choose one.
- 3When the photo appears above the message bar, type your question and tap Send.
CentrusJohn Martin
The boiler in the plant room has stopped. I will send you a photo of the display.
Send it over and I will look up the code in the Riverside House boiler manual.
Centrus may make mistakes. Check important info.
iPhones store photos as HEIC, but convert them to JPEG when you choose one from the camera or library here. A HEIC file copied to a computer first is turned away, so export it as a JPEG before attaching it. For photos taken on site, WhatsApp is often quicker; see Message Centrus on WhatsApp.
Check or remove files before you send
Each file waits above the message bar until you send. Photos show a small preview; other files show a paperclip and their name.
Centrus may make mistakes. Check important info.
- 1A photo, with a preview so you can check it is the right one.
- 2A PDF or spreadsheet, shown with a paperclip and its name.
- 3The cross, which takes that file off the message.
- Click the cross on a file to take it off the message. The rest stay.
- Files waiting here are lost if you open another chat or reload the page, so send them first.
- Always type a line with your files, even a short one such as "What does this code mean?". A message with files but no text is not saved to the chat, so it is gone the next time you open it.
What a sent message shows
Once sent, your files sit under your message. Centrus reads them along with your question and your tags' files in Train, and its answer names the Train files it used as sources.
The boiler in the Riverside House plant room is showing this. What does it mean, and is there anything on last month's service sheet?
The display shows F28, an ignition lockout: the boiler tried to light and failed. Your September service sheet notes that the ignition electrode was worn and due for replacement, so check that first, then the gas supply and the condensate pipe.
Sources:
- • Boiler fault codes.txt
- • Riverside House boiler O&M manual.pdf
- 1A photo, shown as a square. Point at it to see its name.
- 2A PDF or spreadsheet, shown as a card with its name.
- 3Centrus's answer, which takes in your files as well as Train.
You do not need to attach a file again to ask more about it. Centrus keeps it in mind for the rest of the chat, so "What part number is the electrode?" works as a follow-up. Centrus can also use what you attach in the files it makes for you, such as putting a site photo into a report; see Files Centrus makes for you.
Open an attachment later
Click a photo or file card in any message to open it beside the chat. Chat switches to full view, so the menu, page heading and chat list make way for the file.
John Martin
last message sent: 2 minutes ago
Check this quote against our rate card. Is there any line we would not make a margin on?
| Item | Quote | Rate card | Margin |
|---|---|---|---|
| Detector head | £38.50 | £52.00 | £13.50 |
| Detector base | £9.80 | £12.00 | £2.20 |
| 7Ah battery | £18.50 | £18.50 | £0.00 |
The battery is quoted at £18.50, the same as the 2026 rate card price, so there is no margin on it. Delivery is not on the rate card.
Sources:
- • Rate card 2026.xlsx
Northgate Fire & Security Supplies Ltd
Unit 4, Canal Wharf, Leeds LS11 5PS · 0113 496 0720
Quotation
Q-2291
Date07/10/2026
Valid until06/11/2026
Delivery toRiverside House
| Description | Qty | Unit | Total |
|---|---|---|---|
| Optical smoke detector head | 4 | £38.50 | £154.00 |
| Detector base, standard | 4 | £9.80 | £39.20 |
| 12V 7Ah sealed lead acid battery | 2 | £18.50 | £37.00 |
| Delivery, next working day | 1 | £12.00 | £12.00 |
Subtotal£242.20
VAT at 20%£48.44
Total£290.64
Prices exclude VAT unless shown. Orders placed by 15:00 are dispatched the same working day.
- 1The file you clicked in the chat.
- 2Its name, type and size.
- 3Open in a new tab, for the file on its own.
- 4Save: to your downloads, to OneDrive or to Google Drive.
- 5Close preview, or press Escape.
- 6The divider. Drag it to give the file or the chat more room.
- PDFs open in your browser's PDF viewer, with its own page and zoom controls.
- Photos open full size in the pane.
- Spreadsheets open as a table, with a tab for each worksheet. Very large sheets show their first 1,000 rows and 60 columns; download the file to see the rest.
- The divider remembers where you left it next time.
- On a phone or a narrow window, the file takes the whole screen, and closing it brings the chat back.
Who can see your attachments
Anyone who can read the chat can see and open its files. Nobody else can, even if they have the same tags.
- John MartinOwns the chatAttaches files, sees them in the chat and opens them
- SPSarah PriceThe chat is shared with herSees the files in the chat and opens them, but cannot add any
- DHDylan HughesLeads John's teamSees the files when he reads the chat from team history
- Everyone elseIncluding people with the same tagsNever sees them. The files are not added to Train or used in other chats
- People you share the chat with see its files but cannot add their own. See Share a chat and see team history.
- Team leaders who read your chat from team history see its files too.
- Attachments do not count towards your organisation's storage in Train.
- Once sent, an attachment stays with its message. There is no way to remove it from a chat, so think twice before attaching anything personal or confidential.
Good things to attach
Attachments work best for one-off files that matter to a single question or job. Pair each one with a clear question.
A fault code on site
A supplier's quote
An export from another system
A data plate or label
- A fault code or warning light: Centrus reads the display and checks the code against the manuals in Train.
- A supplier's quote: compare it line by line with your rate card or contract prices.
- An export from another system: a CSV of readings, costs or job times, for totals, trends and outliers.
- A data plate or label: pick out the model and serial number, then find the right manual or part.
- A screenshot: an error message or a page from another system, pasted straight in.
Files in WhatsApp and Teams
Each place you talk to Centrus handles files differently.
Web chatWhat you can send
PDFs, spreadsheets and JPEG or PNG photos, up to 20 in a message
The paperclip, drag and drop, or paste
WhatsAppWhat you can send
Photos, PDFs and Word documents, with your question as the caption, and voice notes
WhatsApp's own attach and camera buttons
Microsoft TeamsWhat you can send
Text only. Files, photos and voice messages are not read
Type your question instead
WhatsApp takes photos, PDFs and Word documents with your question as the caption, as described in Message Centrus on WhatsApp. Microsoft Teams reads text only, as described in Chat on Microsoft Teams.
Limits and messages
A message can carry up to 20 files. If something cannot be added, a message appears at the top right of the screen.
Maximum files reached
You can upload a maximum of 20 files per message.
20 files are already waiting above the message bar.
Some files skipped
Only the first 5 files were added (maximum 20 per message).
You chose more files than there was room for.
Unsupported file type
File "Site survey.docx" has an unsupported format.
Not a PDF, spreadsheet, JPEG or PNG, or the model does not read it.
Upload failed
Failed to upload "Fire door schedule.pdf". Please try again.
The file could not be stored. Try it again on its own.
- 20 files a message. Choose more and only the first 20 are added.
- About 30 uploads a minute. Adding a large batch in quick succession can trip this, and the extra files fail. Wait a minute and add them again.
- Size. There is no set limit, but very large files are slow and can fail. Split a long PDF or trim a big spreadsheet to the part you need.
- A failed upload shows two messages, one naming the file and a general one. Try the file again on its own.
