LabLink 2.2.1

🐛 Fixed

• Selecting an oscilloscope on the Control tab stopped the other instruments
  connecting. The tab drives power supplies, so it polls for volts and amps;
  a scope has no setpoints and the server answers 501 Not Implemented -- five
  times a second, forever. That storm saturates the event loop and starves the
  connect task, so the supplies on the same bench then fail to connect, which
  looks like an unrelated fault and is how it was found. The 2.1.4 fix stopped
  this for a missing instrument but treated every other status as transient,
  on the reasoning that a 5xx means the server is unwell and a supply should
  read through it. True of 500 and 503; not of 501, which is a permanent
  statement about the instrument. The two stay separate: a missing instrument
  is marked disconnected, while one that simply has no setpoints is left
  connected and says so, since calling a healthy scope disconnected would be a
  lie the Equipment tab repeats.