Siemens HydroRanger 200 HMI, Руководство по эксплуатации, Страница: 314 / 404

Technical reference
A.13 Current output function
HydroRanger 200 HMI
312
Operating Instructions, 06/2018, A5E36281317-AC
A.13 Current output function
Current output function (2.5.3.) (Page 181) controls the mA output and applies any relevant
scaling. By default, it is set to Level. Other options are Space, Distance, Volume, Flow, or
Head.
You can also set the mA output to report when the device is in an error condition and the fail-
safe timer has expired. By default, the reported value depends on the device type. A
standard device reports the last valid reading, and a NAMUR NE43 compliant device reports
the user-defined value for mA Fail-safe value (2.4.9.) (Page 180) (3.58 mA by default).
A.14 Loss of echo (LOE)
A loss of echo (LOE) occurs when the calculated measurement is judged to be unreliable
because the echo confidence value has dropped below the echo confidence threshold.
If the LOE condition persists beyond the time limit set in LOE timer (2.4.2.) (Page 177), the
display shows the Service Required icon, and the text region displays the fault code 0 and
the text LOE.
If two faults are present at the same time, the device status indicator and text for the highest
priority fault will display. For example, if both loss of echo and broken cable faults are
present, the broken cable fault will display.
A.15 Fail-safe mode
The purpose of the Fail-safe setting is to put the process into a safe mode of operation in the
event of a fault or failure. The value to be reported in the event of a fault [as displayed in
Milliamp output (2.5.9.) (Page 182) is selected so that a loss of power or loss of signal
triggers the same response as an unsafe level.
LOE timer (2.4.2.) (Page 177) determines the length of time a Loss of Echo (LOE) condition
will persist before a Fail-safe state is activated. The default setting is 100 seconds.
Material level (2.4.5.) (Page 178) determines the mA value (corresponding to the selected
PV) to be reported when LOE Timer (2.4.2.) (Page 177) expires.
Upon receiving a reliable echo, the loss of echo condition is aborted, the Maintenance
Required icon and error message are cleared, and the mA output return to the current
material level. [The Primary reading on the HMI display will show dashes (– – – – – – –) when
a fault that causes fail-safe is present, and will return to the current reading when the fault is
cleared.]