Servomex DF-130E, Operator'S Manual

Page: 47 / 88

Outputs and Remote Connections DF-150E 43
9.1.2 4 to 20 mA Isolated Output
(4-20+, 4-20-)
The optional 4 to 20 mA output is proportional to the oxygen reading of the
analyzer. The output on a three range analyzer, will be scaled to the currently
selected range.
An output of 4 mA represents an operating analyzer with zero detected
oxygen. Outputs ranging from 4 to 20 mA represent oxygen concentrations
from zero to the top of the currently selected range.
The 4 to 20 mA output is electrically isolated from all other analyzer outputs
and from the chassis (earth) ground.
The maximum load resistance is 1K Ohms. The analyzer provides a loop
supply of approximately 28 VDC.
Connections to the 4-20 mA output should be through a shielded, twisted pair
with the shield tied to the nearest ground stud.
9.1.3 Analog Output
(Rec + & Rec - )
The default setting for the analog output is 0 to 10 VDC. Alternate settings
available when ordering are 0 to 1 VDC, 0 to 2 VDC or 0 to 5 VDC. See the
sticker on the inside of the front door, Figure 7, for the current setting of the
analog output voltage.
The analog output is proportional to the oxygen reading of the analyzer and on
a three range analyzer will be scaled to the “selected” range.
The minimum load impedance is 10K Ohms.
Connections to the analog output should be made through a shielded, twisted
pair with the shield tied to the nearest ground stud to the terminals labeled Rec
+ and Rec -.
9.1.4 Remote Range Indicator
(Range Com - Range 1, 2, 3)
The analog output is proportional to the oxygen reading of the analyzer. On
three range analyzers, the output will be scaled to the currently selected range.
Similarly, alarm settings are also range specific. If the range is changed up or
down then the alarm value will increase or decrease by a factor of ten.
If the analyzer has three ranges and the analog output is being sent to a
recorder or other remote device, it will be necessary to also send a Range
Indicator so the remote reading can be properly scaled.
The Remote Range Indication is a contact closure between Range Com and the
selected range with the lowest range being contact #1 and the highest range
being contact #3.
The contacts are rated at 24 VDC, .5 Amps.