Hello support team,
I'm encountering significant issues with the Feetech RS485 servo Skill update after upgrading to ARC version 2026.02.19.01.
I have two robots equipped with a total of 38 Feetech servos, model STS32125-12V. After updating, none of these servos are functioning. To troubleshoot, I ran a test with a single servo, #1, connected to COM port 29. However, assigning the address is proving impossible. Please refer to the attached screenshot.
I am seeking a way to revert the update to get everything operational again, or if there is an alternative solution available, I would appreciate your guidance.
Thank you very much.
Error message:
Timestamp: 2026-02-21 21:14:05 UTC
ARC Version: 2026.02.19.01
OS Version: Microsoft Windows NT 10.0.26200.0
Base Directory: C:\Program Files (x86)\Synthiam Inc\ARC by Synthiam\
=== Exception Information ===
Type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
HResult: -2147467261
Source: ARC
TargetSite: System.Object J9PGK7ifYobwPMGF636k(System.Object)
StackTrace:
at ARC.UCForms.UC.FormPortSelect.J9PGK7ifYobwPMGF636k(Object )
at ARC.UCForms.UC.FormPortSelect.AElLCdeY8F6(Int32 )
at ARC.UCForms.UC.FormPortSelect.XLdLCPiILcP(Object , EventArgs )
at System.Windows.Forms.ComboBox.OnSelectedIndexChanged(EventArgs e)
at System.Windows.Forms.ComboBox.set_SelectedIndex(Int32 value)
at System.Windows.Forms.ComboBox.set_SelectedItem(Object value)
at ARC.UCForms.UC.FormPortSelect.PgnoNfivILWH6QLQuwNl(Object , Object )
at ARC.UCForms.UC.FormPortSelect.JOvLCxoVcnv(Int32 )
at ARC.UCForms.UC.FormPortSelect.SetConfig(ServoDescriptor servo)
at ARC.UCForms.UC.UCPortButton.pgh4CYiE6NEaCcucFRjN(Object , Object )
at ARC.UCForms.UC.UCPortButton.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Rather than revert an update, you should update all plugins as well. Please sure you have updated the robot skill
Sorry, I don't quite understand the answer.
I've opened a new program for testing. It only contains Servoskill and the horizontal slider.
What else needs to be updated?
And how?
I think what they’re saying is you need to update the robot skill.
That's exactly what I did along with the update. Skills Fetech serial and RS 485 were updated. Would a complete reinstall help?
Shouldn’t need a reinstall. I’ll have to poke around and see if it’s missing something