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Fix Connection Failed Message

Do you keep getting the “Connection failed” message when try to connect your Select Mini V2 via USB even though the printer is detected by S3D.

"Attempting connection at \\.\COM5...
   Testing plaintext communication protocol...
   Testing binary communication protocol...
   Testing alternate communication protocols...
   Connection failed."

This may help with that. Simplify3D needs a small change made to the “Flow Control” setting located in the “Advanced” section of the “Communications” tab which can be found in the “Firmware Configuration” settings. The “Flow Control” drop-down has three options:

  • No Flow Control
  • Hardware Flow Control (RTS/CTS)
  • Software Flow Control (XON/XOFF)

Choosing either the hardware or software options seems to work. The only difference made in the S3D firmware profile is to the “Flow Control” setting which is set to “Hardware Flow Control (RTS/CTS)”.

Import FRM Profile


  1. Extract the contents of the downloaded zip file.
  2. Click Tools from the menu bar.
  3. Click Firmware Configuration from the Tools drop-down.
  4. Click Import.
  5. Choose the MP Mini 3D Printers.frm file from the download location.
  6. Click Save.
    1. If a warning dialog box is displayed, read the warning message and click Okay.
  7. Locate the Processes section.
  8. Click Edit Process Settings to open the FFF Settings window.
  9. Choose your printers profile from the Select Profile: drop-down.
  10. Click the Show Advanced button.
  11. Switch to the G-Code tab.
  12. Locate the Update Firmware Configuration section.
  13. Choose MP Mini 3D Printers.frm from the Firmware type drop-down.
  14. Click Update Profile which is located next to the Select Profile: drop-down.
  15. Click OK.

Simplify3D Firmware Profile for MP Mini 3D Printers
This firmware profile will allow S3D to connect to the MP Select Mini V2 and MP Mini Delta.
(MP Select Mini V1 connects with or without this firmware.)


This will temporarily connect but then the printer becomes unresponsive.

  1. Click Tools from the menu bar.
  2. Firmware Configuration from the Tools drop-down.
  3. Switch to the Communication tab
  4. Locate the Communication Settings section.
  5. Uncheck Wait for startup command.
  6. Click Save and a warning dialog box will appear.
  7. Read the warning message and click Okay.
slicers/s3d.txt · Last modified: 2017/12/09 05:39 by Matthew Upp