Connection Mode for Duet 3 Mini 5+ Ethernet with Raspberry Pi 5
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Hello,
We are using the Duet 3 Mini 5+ Ethernet and need advice on the best connection mode to use with a Raspberry Pi 5. So far, we’ve identified three potential approaches:
Direct USB Mode
- Minimal components required.
- USB connection to the Duet.
- No SD card needed.
- G-code is sent to and executed on the Duet.
Standalone Mode
- Duet operates from an SD card.
- DuetWebControl available.
- Macros and configuration files are stored on the SD card.
- USB connection and G-code execution work similarly to Direct USB Mode.
SBC Mode
- Serial connection between the Pi and Duet.
- Some processing tasks are offloaded to the Raspberry Pi.
- Macros and configuration files are stored on the Pi.
- G-code execution is similar to other modes but requires selecting the serial port.
Questions and Considerations:
We have some restrictions, requirements, and open questions that need addressing:- SD Card Reliability and Security
Concern: SD cards could fail, potentially disabling the machine and requiring professional servicing (which we want to avoid).
Security Concern: Someone might access the SD card, read stored information, or modify settings, which is unacceptable. - Connection Reliability
Which connection type (serial or USB) is more reliable for communication? - SBC Mode and Raspberry Pi Performance
We already run multiple tasks on the Raspberry Pi.
How much computing power does SBC mode require? Could it overload the Pi? - Error Handling and Machine Status Updates
In SBC mode, the browser interface allows monitoring of machine status and receiving error notifications.
Are these features (status updates, error notifications) still available in Direct USB Mode or Standalone Mode?
Is there a way to receive error/machine status notifications proactively, or must we request updates through G-codes? - Custom Machine Configuration in Direct USB Mode
How are machine configuration settings saved?
Is custom firmware compilation required in this mode? - Ribbon Cable Pin Usage
We need additional UART and SPI connections from the Raspberry Pi, but the standard ribbon cable blocks all GPIO pins.
Which pins are used by the ribbon cable?
Are other UART and SPI connections still available for use? - Object Model Features
Are any object model features missing when using Direct USB Mode?
Would you be able to answer our questions and make a suggestion, which mode of operation is most suitable?
Although it would be helpful to understand our whole setup, I can unfortunately not disclose much more information, as we are an industrial customer and information is confidential. We do have an NDA with Duet3d, but I could see on the website that technical support is only given in the forum. Would you be able to also provide individual technical support to us, perhaps in a TEAMS meeting?Best Regards
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@TobiAsis I will reply via email as some questions are rather specific to your application
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@T3P3Tony Thanks Tony, much appreciated!
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@T3P3Tony said in Connection Mode for Duet 3 Mini 5+ Ethernet with Raspberry Pi 5:
@TobiAsis I will reply via email as some questions are rather specific to your application
Would still appreciate any general comments in the forum for usage notes of RPi5 with either Duet3 Mini 5 or 6HC/6XD boards. Thanks!
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@Dude8 we don't recommend feeding the Duet commands via USB. If you do that then when you want to pause and resume the print (or if a filament error is detected and this causes a pause), all moves that are currently queued on the Duet will be completed first, due to the serial nature of the USB interface. Whereas if you use the SPI connection and SBC mode, pausing can cancel moves that have already been queued. This is possible because the Duet can communicate to the SBC where the job file needs to be restarted from.
Also, using SBC mode means that the SBC has full access to the object model; whereas if you send commands over USB then you need to use M409 if you want to retrieve values from the object model, and the M409 command may get delayed because of other commands already in the USB buffer. So the M409 response may be delayed a little and the values will be less up to date. Similarly if you use M105, M114 etc. to retrieve other information about the state of the machine.
To tell the Duet to run in SBC mode you remove the SD card from it, so there is no SD card wear at the Duet end.
