Installation
Outputs
41
5
5.7.2 Analog Output
The analog output can be set to 0-20 mA or 4-20 mA current range. Direct connection to a recording device (e.g.,
chart recorder, PLC, or controller) is possible. The total analog output circuit impedance is limited to 500
Ω.
For the principle wiring, use the installation scheme below.
Figure 5-13: Wiring the Analog Output
A specific feature for the testing or calibrating of connected equipment allows the current loop output to be set to
specific values, under range or over range using a dedicated ASCII command. Via such functionality, you can force
the instrument, operating in the 4-20 mA mode, to transmit an output current less than 4 mA (e.g., 3.5 mA) or
above 20 mA (e.g., 21.0 mA).
Current Calculation
The sensor converts each measured temperature to a current equivalent. By default, the current equivalent
corresponds to the measuring range of the sensor. However, the current output can also be scaled to a subrange
defined by the user.
The following formula demonstrates the output current calculation regarding the given measurement subrange.
T
Up
– upper temperature of subrange, e.g. 2000°C
T
Lo
– lower temperature of subrange, e.g. 1000°C
I
Up
– upper current of current output range, e.g. 20 mA
I
Lo
– lower current of current output range, e.g. 4 mA
T
Meas
– actual measured temperature, e.g. 1500°C
I
Meas
– actual calculated and output current
I
Meas
= I
Lo
+
I
Up
− I
Lo
T
Up
− T
Lo
∙ (T
Meas
− T
Lo
) = 4mA +
20mA − 4mA
2000°C − 1000°C
∙ (1500°C − 1000°C) = 12mA
A
V
DC
+
+ mA Out (J)
- mA Out (K)
Ground (L)
+ 24 VDC (M)
Sensor
