Celec LTR7000 User manual

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 1
LEVEL TRANSMITTER
LTR7000
INDUSTRIAL ELECTRONICS

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 2
CONTENTS
1. PRECAUTIONS!................................................................................................................................................3
2. MANUFACTURER WARRANTY, GENERAL TERMS AND CONDITIONS...................................................4
3. DISPOSAL OF OLD ELECTRICAL & ELECTRONIC EQUIPMENT .................................................................5
4. LEVEL TRANSMITTER LTR7000.....................................................................................................................5
5. GENERAL DESCRIPTION ................................................................................................................................6
6. FEATURES.........................................................................................................................................................8
7. LTR7000 OVERVIEW & CONFIGURATION ................................................................................................11
8. INSTALLATION..............................................................................................................................................14
9. ELECTRICAL SECTION...................................................................................................................................17
10. CALIBRATION PROCESS - DEFAULT SETTINGS........................................................................................22
11. DIMENSIONS.................................................................................................................................................27
12. TECHNICAL SPECIFICATIONS .....................................................................................................................28

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 3
1. PRECAUTIONS!
There are no serviceable parts inside the LTR7000 unit. Not to be opened by any
unauthorized person. Any repair, modification, or configuration of the device must be
carried out by the manufacturer, or a qualified service engineer familiar with the application.
Improper handling may result in serious personal injury and considerable material
damage. All connection and maintenance work must be carried out by qualified personnel.
RISK OF ELECTRIC SHOCK!
Use the correct voltage. The LTR7000 is designed for use
with specific voltage only. Connection to a different voltage
may cause fire, electric shock or other damage.
Do not touch electronic parts and connection cabling with wet hands.
Disconnect power supply from the LTR7000 before maintenance or configuration, to
avoid the risk of electric shock.
Attempting to use a malfunctioning LTR7000 can be dangerous.
Install the LTR7000 in an appropriate area.
LTR7000 consists of a waterproof stainless-steel tube and an IP66 polycarbonate enclosure
with cable gland, which makes it appropriate for harsh industrial environment. Though if
possible, it is recommended to keep the installation area protected from unnecessary
harmful conditions like extremely high/low temperature, steam etc.
If there is suspicion of small object or liquids into LTR7000, unplug the unit immediately.
Have the unit checked by a qualified service engineer before using it again. Any object or
liquid inside the enclosure may result to fire, electric shock, or equipment damage.
Always follow the instructions given by the manufacturer and use the LTR7000
in accordance to its specifications.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 4
2. MANUFACTURER WARRANTY, GENERAL TERMS AND CONDITIONS
Thank you for purchasing our product.
Our products have been manufactured with the latest technology, the highest quality
components and have gone through rigorous quality control tests at the factory, before
shipment. Make sure that the part number/type indicated on the identification label and
package corresponds to the part number/type of your order. After receiving the unit,
inspect it in order to ensure that no damage was caused during transportation.
GELEC and GELEC’s authorized distributors warrant to the original purchaser that the
product shall be free from defect in material and/or workmanship. The warranty period
begins on the purchase date (proof of purchase by invoice or delivery note) and is valid for
one (1) year.
In the event of malfunction during the warranty period, attributable directly to faulty
material and/or faulty construction and functional defects, GELEC and authorized
distributors will, at their option, either repair or replace the faulty product with the same or
similar model.
GELEC and authorized distributors shall have no obligation under this warranty, however, in
the following cases:
Any defect caused by freight damage, accident, disaster, faulty maintenance or
improper handling.
Any defect caused by modification, alteration, abuse, misuse, or incorrect installation.
Any defect of the product caused by improper repair by third party other than GELEC
and GELEC's authorized distributors.
Any incompatibility of the product with subsequent technical innovations or
regulations.
Any defect of the product caused by external equipment.
Any defect of the product on which the original manufacturer’s labeling has been
altered or removed.
In case of complaint please contact our company, or send the unit un-dismantled to your
local dealer. Any necessary replacement parts and necessary repair work are covered free of
charge.
All products are designed and produced by the manufacturer GELEC Co. LP to be in
compliance with the EU norms applying to them. GELEC is not responsible for direct or
indirect damages or malfunction caused by improper use or installation of the LTR7000.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 5
3. DISPOSAL OF OLD ELECTRICAL & ELECTRONIC EQUIPMENT
This symbol, found on your product, indicates that this should not be
treated as household waste when you wish to dispose it.
It should be handed over to an applicable collection point for the
recycling of electrical and electronic equipment.
By ensuring this product is disposed of correctly, you will prevent
potential negative consequences to the environment and human
health, which could otherwise be caused by inappropriate disposal of this product.
The recycling of materials will help to preserve natural resources.
4. LEVEL TRANSMITTER LTR7000
This operator's manual explains the functions and operation of the LTR7000. It also gives
some troubleshooting tips as well as general precautions to be taken when operating the
unit. In order to ensure the best performance and effective use of the LTR7000, we
recommend that you read the information in this manual carefully and follow the
instructions contained.
This manual is a complete guide for the LTR7000 with information on unit user
maintenance, unit installation and operational instructions. Do not touch parts of the
LTR7000 that are not referred in this manual. Keep this manual for immediate reference. It
should help in solving any operational questions you may have.
No part of this manual may be quoted, reproduced, stored in a retrieval system,
transmitted, transcribed or translated into any other language in any form or by any means,
electronic, mechanical, or otherwise, without prior written permission of “Gelec Co. LP”.
Although every effort has been made to ensure that this manual provides up to date
information, please note that the contents of this manual and unit specifications are subject
to change without notice.
Don’t forget to mention the exact type and version of
your LTR7000 whenever you contact the manufacturer
asking for any further information. You can find this
information on the identification label of the unit.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 6
5. GENERAL DESCRIPTION
The LTR7000 is an industrial, rangeable resistive chain level transmitter, suitable for non-
invasive level measurement in open or closed tanks. Its operation is based on the magnetic
floating principle and communicating vessels.
A magnetic float inside a measuring chamber mounted to the application tank, follows the
fluid level changes during process. Having an array of closely spaced hall effect sensors, the
LTR7000 senses the float’s position and therefore the height of the fluid level. It provides a
continuous, linear current and voltage output signal (4-20, 0-20, 4-21mA / 0-5, 0-10V),
proportional to the level height and available for further processing.
The two output signals can be utilized simultaneously or independently and their respective
output range is selected through a dip-switch. LTR7000 zero and span settings can be easily
rescaled in order to meet each application’s operating requirements, while factory default
settings can be restored at any time.
It consists of a stainless-steel square tube which incorporates the sensor chain and a
fiberglass reinforced polycarbonate enclosure, including the microprocessor based
transmitter and the connection terminal block.
With 7mm sensing resolution and a variety of standard analog signals that can be assigned
by the user to any level range up to 205cm, the LTR7000 is an ideal solution for industrial,
heavy-duty level measurement applications.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 7
MAIN FEATURES
High measuring accuracy (7mm resolution) in industrial environment
Five length versions available (65/100/135/170/205 cm)
Two analog outputs (mA/V)
Five signal standards available (4-20, 0-20, 4-21mA / 0-5, 0-10V)
12mT (120 Gauss) sensor sensitivity - North pole activated
Separate calibration of High and Low critical levels
Error state recognition with relevant output signal
Status LED, calibration button, configuration dip-switch
Factory calibrated to full measuring range
Factory default settings can be restored
Stainless steel square tube 12x12mm
IP66 robust and durable structure
15-36 VDC / 2.5W max
Protective circuit against reverse polarity
ADVANTAGES
Reliable and cost effective operating philosophy
Unaffected from media variables (foam, viscosity, dielectrics, pressure, pH etc.)
Proper for special conditions (surface agitation, boiling, high empty/fill rates etc.)
Suitable for process/storage vessels with non-magnetic measuring chamber
Ideal for high-temperature and high-pressure applications

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 8
6. FEATURES
LTR7000 VERSIONS
LTR7000 is provided in five length versions, depending on the maximum level height that
the device can measure. The resolution is the same in all versions, while the different length
options cover a wide range of installation configurations.
LTR7065
LTR7100
LTR7135
LTR7170
LTR7205
Measured level height
0-65 cm
0-100 cm
0-135 cm
0-170 cm
0-205 cm
Total device height
79 cm
114 cm
149 cm
184 cm
219 cm
Sensor resolution
7 mm
TWO ANALOG OUTPUTS / FIVE OUTPUT RANGES AVAILABLE
LTR7000 provides two analog outputs (mA & V) which can be used either simultaneously,
or independently. There are five common output signal standards available, covering the
majority of process control applications.
The selection of the desired output range can be made from the internal configuration dip
switch (SW1/SW2/SW3). The available output ranges are the following.
mA output ranges :
4 - 20 mA , 0 - 20 mA , 4 - 21 mA
V output ranges :
0 - 10 V , 0 - 5 V
Each output range change, forces the device to properly reconfigure its output linearization.
Notice that the output signal cannot get values outside the selected range, even if the
application fluid (and therefore the floating magnet) exceeds the calibrated operating
region.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 9
SIMPLE CALIBRATION PROCEDURE / DEFAULT SETTINGS
LTR7000 standard versions are factory calibrated in order to exploit the whole length of
their active measuring segment. So, the minimum output signal of the selected output
range is provided when the float’s magnet is aligned with the lowest point of their sensor
chain (bottom engraved line on the tube), while the maximum output signal is provided
when the float’s magnet is aligned with the highest point of their sensor chain (top
engraved line on the tube).
The factory calibrated level ranges are the following.
LTR7065 :
0-65cm
LTR7100 :
0-100cm
LTR7135 :
0-135cm
LTR7170 :
0-170cm
LTR7205 :
0-205cm
By following a simple calibration procedure, LTR7000 can be calibrated to provide its output
ranges in different level limits than the factory pre-calibrated ones. There is also the option
to restore the default factory calibration settings at any time, if needed. Refer to the
relevant section for more information.
TWO ERROR STATES - ERROR OUTPUT
LTR7000 is designed to detect and manage two Error states that are likely to occur.
As long as the device is in Error state, the STATUS LED indicates the problem and a
signal almost equal to power supply voltage (VPS-1V) is provided through the ERROR
OUTPUT for further utilization.
If the ERROR OUTPUT cannot be used due to application restrictions, there is the option to
get an error signal from the mA output as well. The device can provide an ‘out of range’
24mA signal, which can be recognized as an error signal from the connected PLC. The
output signal value (min or max) during an Error state can be selected from the internal
configuration dip-switch (SW4), depending on the application needs. Refer to the relevant
section for more information.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 10
ERROR 1 - STATUS LED FLASHING RED (3Hz)
Check the device for the following possible problems.
mA OUTPUT OPEN CIRCUIT
A simple way to confirm an open circuit, is to cut power supply, disconnect the external
circuit from the mA output and short-circuit terminals #3 and #4 with a cable. Turn on the
power for a few seconds, the problem should be solved and the LTR7000 should not be in
Error state. Check the external circuit for disconnections.
Notice that if you are using only the V output, a 390Ωresistor must be connected at the mA
output (terminals #3 and #4). Consult the relevant connection diagram and confirm that
this resistor is properly connected.
HIGH LOAD RESISTANCE RL
The load resistance value connected to mA output (including line resistance), may be higher
than it should be. Refer to the relevant table and confirm that the externally connected
circuit has the proper resistance value.
INTERNAL OVERHEATING
Internal overheating is unlikely to occur and may be caused due to wrong electrical
connections, excessive temperature in the installation area, or LTR7000 hardware damage.
Confirm that all connections and installation environment meet the device specifications.
ERROR 2 - STATUS LED FLASHING RED (1Hz)
THE FLOAT IS MAGNETICALLY UNCOUPLED FROM THE ACTIVE MEASURING SEGMENT, OR
INTERNAL HARDWARE FAILURE.
The float must have an adequate magnetic field and move within the sensor chain range
(vertical and horizontal axis) at all process stages. Ensure that the LTR7000 has not been
moved from its proper installation position. Inspect the measuring chamber and the
magnetic float for defects, or replace the magnetic float and try again. If the measuring
chamber is significantly wider than the float, the float can be out of sensor range within the
chamber.
Check electrical connections and disconnect/reconnect power. If this error remains, the
device has a non-repairable damage. Hardware failure is the most possible cause. Before
replacing the damaged device with a new one, ensure that any possible problem that could
have caused the hardware failure (e.g. wrong connections) is solved.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 11
7. LTR7000 OVERVIEW & CONFIGURATION
The LTR7000 is a level transmitter with a 6-pole terminal block, a calibration button, a
configuration dip-switch and a status LED. Its consists of a 12x12 mm AISI 304 stainless
steel square tube and an IP66 fiber-glass reinforced polycarbonate housing with all-round
foamed-in PU seal, proper for electronic devices exposed in harsh industrial environment. It
is designed to be installed outside the measuring chamber of a process tank.
CALIBRATION BUTTON
The calibration button inside the transmitter enclosure, is used in LTR7000 calibration
process and when the calibration settings need to be reset to default. This button must be
used by an engineer familiar with the device operation and the application in general.
Refer to the relevant sections in this manual for more information.
CONFIGURATION DIP SWITCH
The internal 4-position dip-switch specifies the output range of the LTR7000 analog outputs
(mA/V) and their output value during ERROR state. Dip-switch adjustments must not be
done when the device is powered. Disconnect power supply, open the enclosure and
proceed to switch adjustments according to the following information. If there is not a
dip-switch inside your LTR7000 version, consider all switches being at OFF position.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 12
SW1/SW2 switches (mA output range selection)
With SW1/SW2 switches you can select the mA output range at terminals #3(+) / #4(COM).
4 - 20 mA → SW1 : OFF , SW2 : OFF (default)
0 - 20 mA → SW1 : OFF , SW2 : ON
4 - 21 mA → SW1 : ON , SW2 : OFF
When this mA output setting is selected, the V output doesn’t have a normal behavior.
Do not use V output when this mA setting is selected.
--- Do not set both SW1/SW2 to ON ---
This setting is used only in manufacturing stages and can lead to device malfunction.
SW3 switch (Voutput range selection)
With SW3 switch you can select the Volt output range at terminals #5(+) / #4(COM).
0 - 10 V → SW3 : OFF (default)
0 - 5 V → SW3 : ON
Ensure that the mA output range is not set to 4-21mA setting (SW1: ON / SW2: OFF).
V output doesn’t have a normal behavior with this mA setting selected and cannot be used.
SW4 switch (Output value during ERROR state)
With SW4 switch you can select the output value during ERROR state, according to the
selected output range. Refer to the ERROR section in this manual, for more information
about the possible errors.
4-20mA
0-20mA
4-21mA
0-10V
0-5V
SW4 : OFF (default)
4 mA
0 mA
4 mA
0 V
0 V
SW4 : ON
24 mA*
24 mA*
24 mA*
10 V
5 V
*You can exploit the ‘out of range’ 24mA output for ERROR recognition from your PLC,
when the dedicated ERROR OUTPUT cannot be used due to application restrictions.
This is an actual advantage only for mA output ranges. For the V output ranges, the output
value options are within the measuring range and cannot be utilized. Though, you can
choose between minimum and maximum output, according to your application needs.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 13
STATUS LED
The STATUS LED inside the transmitter enclosure, indicates various operational stages of
the LTR7000. This LED is useful during connection and calibration stages and it is not visible
during normal operation with the cover screwed on the enclosure. Consult the following
table for quick reference and the relevant sections for detailed information.
LED COLOR
LTR7000 STATUS
GREEN
Device powered - Normal operation
(magnetic float within sensor range)
FLASHING GREEN
High-Level calibration mode
FLASHING BLUE
Low-Level calibration mode
GREEN/RED
Confirmation of calibration processes
FLASHING RED (3 Hz)
ERROR 1
FLASHING RED (1 Hz)
ERROR 2
OFF
Device not powered
ACTIVE MEASURING SEGMENT
Only a specific segment of the LTR7000 square tube includes the measuring hall effect
sensors, and this is defined by two engraved lines at the back side of the tube.
The bottom engraved line is located 3cm above the bottom of the tube in all LTR7000
versions. The top engraved line can be found close to the transmitter enclosure. The
distance between them, depends on the LTR7000 version.
Install LTR7000 in a way that the application’s fluid level (and therefore the float’s magnet)
is constantly within the active measuring segment, in order to have proper operation.
MAGNETIC FLOAT
The used magnetic float must have proper buoyancy, with the incorporated magnet fitted
at the correct position in it. Check the relation between the magnet and the level when the
float is in the fluid. The float must be suitable for the application fluid and process
conditions (pressure, temperature, density etc.). Its shape and dimensions must allow free
and vertical movement in the measuring chamber, as close as possible to the LTR7000.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 14
8. INSTALLATION
In this section, you can find useful information that have to be taken under consideration
during LTR7000 installation. Always follow the recommended instructions and use the
LTR7000 in accordance to its specifications.
INSTALLATION AREA
Having an IP66 fiberglass reinforced polycarbonate enclosure, the LTR7000 is suitable for
use in harsh industrial environment. Though if possible, it’s recommended to keep it
protected from steam, extremely low/high temperatures, direct sunlight and excessive
amount of liquids on the enclosure. Fluid insertion into housing may cause permanent
damage, electric shock or fire.
Install far from strong magnetic fields that could affect the device measurement and
provide sufficient space for maintenance and inspection. Maintain the sensor clean and
never operate it with open enclosure. If the enclosure becomes damaged, disconnect the
device immediately and order a replacement.
The two engraved lines on the LTR7000 (measuring segment) and the float’s magnet can be seen in
the pictures above highlighted in red, along with the proper installation of a fully operating system.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 15
MAGNETIC FLOAT / APPLICATION TANK
The shape of the tank must allow a linear relationship between the fluid volume and the
measured level. Otherwise a proper software must be developed, which will automatically
calculate the filled volume of the tank, depending on the output of the transmitter.
Since there is no direct contact between any part of the LTR7000 and the measured fluid,
the system supports both atmospheric and high-pressure applications. The measuring
chamber’s material must be non-magnetic.
It is recommended to use mechanical stops inside the measuring chamber (ideally
adjustable), in order to restrict the float’s magnet within the LTR7000 active measuring
segment limits, even if the fluid level gets out of these limits in some process stages (tank
draining, overflowing etc.).
The magnetic float must move freely during level alterations and not being blocked by
the measuring chamber, or possible sediments, dirt, dregs etc. Ensure that the float
installation environment allows proper and smooth vertical movement. Partial or full
blockage will cause faulty/misleading readings.
A small magnet (south pole) can be attracted from the incorporated float and stick outside
the measuring chamber following its movement. This will ‘visualize’the float’s position
and behavior inside the chamber and help you to easily confirm the proper correlation
between the level and the float.
The measuring chamber should be cleaned and inspected regularly, depending on the
nature of the measured fluid and the process characteristics. Fluids that create sediments
over time, are most likely to need maintenance more frequently.

User’s & Technical Manual – LEVEL TRANSMITTER LTR7000
GELEC Industrial Electronics PAGE 16
PLACEMENT ON THE MEASURING CHAMBER
The LTR7000 tube contains the hall effect sensor chain and has to be tangent to the
measuring chamber, in order to be as close as possible to the magnetic float. On the back
of the tube, at the side that faces the measuring chamber, there are two engraved lines that
define the active measuring segment (check the relevant section for more details).
In a common installation, the LTR700 is installed with the bottom engraved line at the point
where the magnetic float stands in an empty tank. Notice that this point is not the bottom
of the measuring chamber, but the position of the float’s incorporated magnet.
It may be difficult to specify the exact position of the magnetic float inside the measuring
chamber. In order to find this point and make sure that the magnet will always move within
the LTR7000 measuring segment during process stages, follow the below procedure.
▪Empty the tank, so the magnetic float drops at the lowest possible position
inside the measuring chamber.
▪Having the dip-switch SW4 to ON position and the LTR7000 far from the
measuring chamber and the magnetic float, monitor its output with a
multimeter. At this point, the output provides an error value (24mA), because
the magnet is uncoupled from the sensors.
▪Place the LTR7000 on the measuring chamber in a high position and slowly start
sliding it towards the magnetic float, while checking the multimeter. When the
bottom engraved line reaches the float’s magnet, the LTR7000 output will
change to the minimum value of the selected output range (4mA or 0mA),
because the magnet triggers the first sensor of the active measuring segment.
Continue sliding the LTR7000 1cm more, to safely pass this critical point.
✓Mark this position for the LTR7000 final mounting. This position allows you to
exploit the whole active measuring segment of your version. Re-calibrate Low
Level after the final mounting, in order to precisely get the minimum output of
the selected output range when the tank is empty.

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GELEC Industrial Electronics PAGE 17
9. ELECTRICAL SECTION
ELECTRICAL CONNECTIONS
The LTR7000 is equipped with a 6-pole terminal block.
The terminal block is manufactured to provide resistance to stress, corrosion, cracking,
electrolytic corrosion and screw loosening in case of vibrations. This way, conductor
connections are maintained reliable and maintenance-free in harsh industrial environment.
The conductor’s stripping length should be max 6 mm, with its cross-section within the
following ranges (depending on type). The recommended tightening torque is max 0.2 Nm.
Clamp all types of copper cables without pre-treatment. Do not solder the conductors, as it
affects the proper connection quality. Two conductors with the same cross section make
contact safely in the clamping parts. If necessary, copper ferrules can be used as a
protection against splicing when stranded conductors are wired. In general terms, ensure
that you are having reliable mechanical connection and electrical contact.
CABLE GLAND
At the bottom side of the transmitter enclosure, there is a M16x1.5mm cable gland, for
connection cables with outer diameter Ø4-10mm. Ensure that you have a firm and reliable
final assembly, in order to maintain the IP rating of the enclosure. Do not install cable
glands whilst circuits are live. Similarly, following energizing of the electrical circuits, cable
glands should not be dismantled or opened until the circuit has been safely de-energized.
Rigid solid / flexible stranded :
0.34 - 1.5 mm2
AWG :
22 - 16

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GELEC Industrial Electronics PAGE 18
CONNECTION TERMINALS
Read carefully the following information and refer to the connection diagrams and technical
data, regarding proper wiring of the LTR7000 with the associated equipment.
Confirm that you have proper connections before unit operation. Wrong connections may
lead to permanent device or external equipment damage. Don’t proceed to any connection
modification, while the unit is powered.
TERMINALS #1 - #2 (POWER SUPPLY - VPS)
Connect the power supply (15-36 VDC) to terminals #1 (+) and #2 (-).
Maximum power consumption is approximately 2.5W. There is not an electrical safety fuse
in the internal power circuit. Although there is polarity protection, ensure that you are
applying proper voltage and polarity.
TERMINALS #2 - #6 (ERROR OUTPUT)
Terminals #2 (COM) and #6 (VPS -1V) provide the Error output signal during operation.
An internal High Side Driver provides a voltage output signal during ERROR state, almost
equal to power supply voltage (VPS -1V).
The output current limit is 500mA, while the Current Limit Initial Peak is 3A max.
If you don’t need this output, leave the relevant terminals unconnected. Refer to the
relevant section in this manual for more information.
TERMINALS #5 - #4 (V OUTPUT SIGNAL)
Terminals #5 (VOUT)and #4 (COM) provide the Voltage output signal during operation.
The output range (0…5V / 0...10V) can be selected from the internal configuration dip
switch. Refer to the relevant section in this manual for more information.
The output continuous current limit is 10mA, with an overcurrent protection of 30mA max.
If you are going to use the V OUTPUT without using the mA OUTPUT, you must connect a
390Ωresistor to the mA OUTPUT (terminals 3-4). Check the relevant connection diagram.
For having the signal unaffected from any interference, it is recommended to use a shielded
cable with twisted pair, properly grounded at the side of the signal receiving device.
Ensure that the mA output range is not set to 4-21mA setting. Voltage output doesn’t have
a normal behavior with this mA setting selected and cannot be used.

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TERMINALS #3 - #4 (mA OUTPUT SIGNAL)
Terminals #3 (IOUT) and #4 (COM) provide the mA output signal during operation.
The output range (4-20mA / 0-20mA / 4-21mA) can be selected from the internal
configuration dip-switch.
When 4-21 mA output range is selected, the V output doesn’t have a normal behavior.
Don’t use V output when this mA range is selected.
Notice that, even if the selected maximum output value is 20 or 21mA, this output may be
configured to provide 24mA for ERROR recognition (SW4 at the internal dip-switch).
Refer to the relevant section in this manual for more information.
For having the signal unaffected from any interference, it is recommended to use a shielded
cable with twisted pair, properly grounded at the side of the signal receiving device.
MAXIMUM LOAD RESISTANCE (RL)
The output current is proportional to level height. In order to get proper and linear mA
fluctuation, a maximum load resistance RL(including line resistance) must not be exceeded
depending on the supply voltage (VPS)of the device. Consult the following table for the
maximum load resistance you should have for each supply voltage.
VPS (V)
max RL (Ω)
for 20mA max output
max RL (Ω)
for 24mA max output
15
550
420
16
600
460
17
650
500
18
700
540
19
750
580
20
800
620
21
850
660
22
900
700
23
950
740
24
1000
780
25
1050
820
26
1100
860
27
1150
900
28
1200
940
29
1250
980
30
1300
1000
31
1350
1040
32
1400
1080
33
1450
1120
34
1500
1160
35
1550
1200
36
1600
1240

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LTR7000 Connection Diagram (only mA output used)
LTR7000 Connection Diagram (only V output used)