Pi 2 USB connection to Snapmaker II A350 gives "No more candidates to test" error

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1

Hi there! I want to start off by saying that I think this is a wonderful tool, and I can't wait to get it up and running on my printer!

What is the problem?

I'm trying to connect my Raspberry Pi 2 (maybe that's my problem right there!) running OctoPrint 1.7.3 to a Snapmaker II A350, and when I click on the Connect button, I get the error
"State: Offline after error
No more candidates to test, and no working port/baudrate combination detected."

Everything else works great - the web site is fully functional and very responsive, and the streaming camera works great too.

What did you already try to solve it?

I tried starting it in Safe Mode.
I saw here that it was often a problem with the USB cables, so I tried two different ones. Both are brand new. Neither worked.
I tried all four of the USB ports on the Pi.
I tried using different power cables to the Pi - sometimes I'd also get a low voltage warning, so I kept trying until I got one that didn't give me warning.

Have you tried running in safe mode?

Yes

Did running in safe mode solve the problem?

No

Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!)
octoprint-systeminfo-20220410034027.zip (6.6 KB)

Additional information about your setup

OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible

OctoPrint 1.7.3
OctoPi Version 0.18.0, running on Raspberry Pi 3 Model B Rev 1.2
Printer: Snapmaker II A350
Firmware: Snapmaker2_V1.14.2_20220113

2

A Pi 2 should work fine - but your log says you're using a Pi 3?

Let's check is the Pi is seeing the printer at all

Log into your pi via ssh then disconnect your printer, connect it again, enter dmesg | tail -n 20 and post the output here.

If you need help with ssh connection, follow this guide

username: pi
password: raspberry

3

A Pi 2 should work fine - but your log says you're using a Pi 3?

I noticed that too. No idea what's up with that.

Log into your pi via ssh then disconnect your printer, connect it again, enter dmesg | tail -n 20 and post the output here.

That looks like the problem. There's nothing new at the end of dmesg after I do that which would indicate that anything has changed.

[    9.872313] 8021q: 802.1Q VLAN Support v1.8
[   10.025085] Adding 102396k swap on /var/swap.  Priority:-2 extents:3 across:214420k SSFS
[   10.270636] brcmfmac: brcmf_cfg80211_set_power_mgmt: power save enabled
[   10.686751] SMSC LAN8700 usb-001:003:01: attached PHY driver [SMSC LAN8700] (mii_bus:phy_addr=usb-001:003:01, irq=POLL)
[   10.687058] smsc95xx 1-1.1:1.0 eth0: hardware isn't capable of remote wakeup
[   10.695881] smsc95xx 1-1.1:1.0 eth0: Link is Down
[   11.556217] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready
[   14.090679] Bluetooth: Core ver 2.22
[   14.090782] NET: Registered protocol family 31
[   14.090789] Bluetooth: HCI device and connection manager initialized
[   14.090812] Bluetooth: HCI socket layer initialized
[   14.090824] Bluetooth: L2CAP socket layer initialized
[   14.090842] Bluetooth: SCO socket layer initialized
[   14.101353] Bluetooth: HCI UART driver ver 2.3
[   14.101367] Bluetooth: HCI UART protocol H4 registered
[   14.101443] Bluetooth: HCI UART protocol Three-wire (H5) registered
[   14.101607] Bluetooth: HCI UART protocol Broadcom registered
[   14.350064] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   14.350084] Bluetooth: BNEP filters: protocol multicast
[   14.350107] Bluetooth: BNEP socket layer initialized
pi@octopi:~ $

Darn it, I just bought those cables.

4

yep that's the issue. I can't tell you if it's the cable, the port or the firmware, but as long as the pi doesn't see the printer there is nothing we can do :confused:

Either you got a Raspberry Pi 2 V1.2 which got the same soc as the Pi 3 and overclocked it to 1200MHz or you got a Pi 3 without knowing it :smiley:

5

All roads are indicating that it's the cables. But they are literally brand new.
Granted, they are no-name cables from Amazon, but still, both of them?

They are both USB-A to USB-A cables since the Snapmaker only has a USB-A port.
These are the only USB-A to USB-A cables I have. I bought them for another project (trying to connect an ancient Seagate GoFlex drive to a computer), and they don't work for that either, but I was chalking that up to how old the drive was.

Is there such a thing as a USB-A / USB-A null modem cable? Might I need one of those instead?

Thanks for all your help, by the way!

6

Oh - are you sure that port supports serial connections?
Most of those ports are just for usb drives.

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7

Oh - are you sure that port supports serial connections?
Most of those ports are just for usb drives.

You're right, it's just for a USB drive.
On closer inspection, the printer has two other USB ports: a USB-C that the Snapmaker's original control panel plugs into, and a mini which I'll need to research further.
I'll try plugging the Pi into those two ports and see if either works.

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8

good luck :crossed_fingers:

9

Okay, after finding a working USB-B mini cable that actually works, I can confidently say that my Pi is able to connect to my Snapmaker.

Root cause was that I didn't know (or forgot) that the Snapmaker had a mini USB port.

Thanks again, PrintedWeezl!

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10

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