Standard SCPI Error codes?
Are there standard error codes or are the error codes manufacturing / instrument specific?

Having worked with SCPI for over 20 years, I have never seen such a thing. Maybe &quot;0&quot; for &quot;No Error&quot; is widespread enough to be considered a standard.
Even if there were, most likely only Keysight and National Instruments would follow the standard.
Certainly a simple code like &quot;C01&quot; does not follow the usual practice of recent Keysight instruments to use fairly verbose messages like &quot;137, Unterminated Query&quot;.