23. Fail-safe Dir.

     Sets how analog output and pulse
     output will behave if the device is in
     a critical state.
     The fail-safe direction for pulse
     output is valid for ver. 2.0 and later.
     
     Options for fail-safe analog output
     direction are:
      -- Upscale: Output will be at the
         upper limit.
      -- Downscale: Output will be at the
         lower limit.
      -- None: No special output. Output
         will be uncertain and display
         possibly inaccurate.
     
     Options for fail-safe pulse output
     direction are:
      -- Low: Do not output a pulse.
      -- Hold: Keep the pulse output at
         the value obtaining just before
         the critical condition occurred.