Emerson Process Management GmbH & Co. OHG
3-23
X-STREAM XEFD
Instruction Manual
HASXEDE-IM-EX
07/2017
3
Startup
3.9 Checking the Settings
Tab. 3-1:
Analog Output Signals Settings and Operational Modes
Operation Modes acc. NAMUR NE 43
acquisition system is enabled to distinguish
between the following situations
:
•
valid measured value (signal within range
as per Tab. 3-1)
•
signal out of range (signal slowly rises or
falls towards the limits given in Tab. 3-1,
and holds that value until the concentration
returns to within the measuring range).
•
failure (signal out of range as per Tab. 3-1,
but not 0)
•
severed cable (no signal [0 mA]),
Table 3-1 provides a summary of all available
operational modes.
The common modes for analog outputs do
not support the detection of a failure in the
measurement system. In such a case, the
behaviour of the output signal is undefined:
either the last value is held, or a random value
is sent. System failures cannot be detected
by an external data capture system.
NE43 includes recommendations for such
cases, but also for the configuration of analog
outputs to detect other measurement states.
X-STREAM analyzers incorporate these rec-
ommendations as follows:
Setting “
FailMode
” to
HIGH + 10%
or
LOW –
10%
defines specific
analog output signals in
case of a failure. Since these values are not
output under normal operation conditions, a data
Output signal, if
“OutRange” “FailMode”
Failure sig-
nal level acc.
NE 43
Measured
value is
valid
Measured value is
below lower limit
(“Low scale”)
Measured value is
above upper limit
(“High scale”)
An internal
failure oc-
cured
Cable is
severed
0-20 mA
Track
-
0…20 mA
< -19 mA
> 21.7 mA
undefined
0 mA
4-20 mA
Track
-
4…20 mA
< -19 mA
> 21.7 mA
undefined
0 mA
0-20 mA
LOW – 10 %
below
0…20 mA
-0.20 mA*
(-1.80…-0.01 mA)**
20.50 mA*
(20.01…21.50 mA)**
-2 mA
0 mA
4-20 mA
LOW – 10 %
below
4…20 mA
3.80 mA*
(2.20…3.99 mA)**
20.50 mA*
(20.01…21.50 mA)**
2 mA
0 mA
0-20 mA
HIGH + 10 %
above
0…20 mA
-0.20 mA*
(-1.80…-0.01 mA)**
20.50 mA*
(20.01…21.50 mA)**
> 21.7 mA
0 mA
4-20 mA
HIGH + 10 %
above
4…20 mA
3.80 mA*
(2.20…3.99 mA)**
20.50 mA*
(20.01…21.50 mA)**
> 21.7 mA
0 mA
Note!
The application of values marked * or ** depends on the setting of “Cut Mode” (for more information
Chapter 6 of the X-STREAM
Enhanced
instruction manual).
