Applications Guide
Modline 5
129
8
Applications Guide
8.1
Introduction
This section offers guidelines to assure measurement accuracy and reliability. Although it is impossible
to cover every application in detail, the general information provided can be adapted to most situations.
If you run into other situations that may cause problems, consult the IRCON Applications Engineering
Department.
8.2
Analog Outputs
All Modline 5 Sensors provide an analog current signal output of 0 to 20 mAdc or 4 to 20 mAdc. The
output range is selected using the Sensors rear panel AOUT and SOUT function menus or RS-485 Digital
Communications command codes. This current output will drive remote current meters, recorders and
other devices calibrated to read dc milliamps and scaled to convert the analog signals to temperature.
Multiple devices (Loads) can be connected in a series current loop configuration. The maximum series
resistance that can be connected in the loop is 600 Ohms. This maximum includes the resistance of all
devices and cables. See
The minus side of the Analog Output is connected to power supply common (See Section 4.9
Multi-Drop Network Power Supply and System Wiring
, page 75 of this manual about Sensor
Grounding). Use instruments with ungrounded differential inputs. If instruments with grounded
inputs are connected in the loop, the output may be inoperable or inaccurate.
If the Analog output is not used, insert a jumper wire across the output terminals. This will prevent an
Analog Loop malfunction (open circuit) Alarm (Error X108) from occurring.
The current signal varies linearly with the measured temperature. There are several schemes for
temperature scaling these outputs current. The standard scaling is when the output zero scale current
and full scale current is scaled to equal the Sensor’s zero scale and full temperatures. Alternate
temperature scaling can be accomplished using the Sensor’s AOUT Main Menu the ZERO and FULL
functions. See Section 5
, page 82 of this manual for instructions. The paragraphs and diagram
below provide further explanation.
The ZERO function sets a temperature to correspond to the selected Analog Output Current Range
minimum value (0 or 4 mA). This temperature must be within the Sensor’s specified temperature range
and is limited to a maximum value 10° below the Sensor’s specified full scale temperature. Minimum
setting is the Sensors’ specified zero scale temperature.
The FULL Sets a temperature to correspond to the Analog Output Current Range maximum value (20
mA). Temperature must be within the Sensor specified temperature range and is limited to a minimum
value 10° above the Sensors’ specified zero scale temperature. Maximum setting is the Sensor’s specified
full scale temperature.
