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CNGmass DCI
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Endress+Hauser
5.3.3
Confirming error messages
For the sake of plant and process safety, the measuring device can be configured in such a way that
fault messages displayed ($) always have to be rectified and acknowledged locally by pressing F.
Only then do the error messages disappear from the display.
This option can be switched on or off by means of the "ACKNOWLEDGE FAULT MESSAGES"
function (È "Description of Device Parameters" manual).
Note!
• Fault messages ($) can also be reset and confirmed via the status input.
• Notice messages (!) do not require acknowledgment. Note, however, that they remain visible
until the cause of the error has been rectified.
5.4
Communication
In addition to local operation, the measuring device can be configured and measured values can be
obtained by means of the HART protocol. Digital communication takes place using the 4 to 20 mA
current output HART → ä 20.
The HART protocol allows the transfer of measuring and device data between the HART master and
the field devices for configuration and diagnostics purposes.
The HART master, e.g. a handheld terminal or PC-based operating programs (such as FieldCare),
require device description (DD) files which are used to access all the information in a HART device.
Information is exclusively transferred using so-called "commands".
There are three different command groups:
• Universal Commands
These are associated with the following functionalities for example: Universal commands are
supported and used by all HART devices.
– Recognizing HART devices
– Reading digital measured values (volume flow, totalizer etc.)
• Common Practice Commands
Common practice commands offer functions which are supported and can be executed by most
but not all field devices.
• Device-specific Commands
These commands allow access to device-specific functions which are not HART standard. Such
commands access individual field device information, amongst other things, such as empty/full
pipe calibration values, low flow cut off settings etc.
Note!
The measuring device has access to all three command classes.
List of all ''Universal Commands" and "Common Practice Commands": → ä 31.
Operation
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