Aplisens LI-24L User manual

USER’S MANUAL
TEMPERATURE TRANSMITTERS
LI-24L Safety
LI-24G Safety
EN.IO.LI.24.L.G.SFT
AUGUST 2021
APLISENS S.A., 03-192 Warsaw, Morelowa 7 St,
tel. [phone]; fax [phone]
www.aplisens.com, e-mail: [e-mail]
Revision 02.A.004

PRODUCT CODE –see ➔5.2. Transmitter identification.
The QR code or ID number identifies the transmitter and provides quick access to the following docu-
mentation on the manufacturer’s website: user’s manual, SIL safety manual, explosion-proof device
user manual, declarations of conformity and copies of certificates.
LI-24L Safety
ID:0003 0005 0003 0000 0000 0000 0001 26
https://aplisens.pl/ID/000300050003000000000000000126/00000000
LI-24G Safety
ID:0004 0006 0003 0000 0000 0000 0001 89
https://aplisens.pl/ID/000400060003000000000000000189/00000000

Symbols used
Symbol
Description
Warning to proceed strictly in accordance with the information contained in the doc-
umentation in order to ensure the safety and full functionality of the device.
Information particularly useful during installation and operation of the device.
Information particularly useful duringinstallation and operation of an Ex type device.
Information on disposal of used equipment.
BASIC REQUIREMENTS AND SAFE USE
The manufacturer will not be liable for damage resulting from incorrect installation,
failure to maintain a suitable technical condition of the device or use of the device
other than for its intended purpose.
Installation should be carried out by qualified staff having the required authorizations
to install electrical and I&C equipment. The installer is responsible for performing
the installation in accordance with manual as well as with the electromagnetic com-
patibility and safety regulations and standards applicable to the type of installation.
All safety and protection requirements must be observed during installation, opera-
tion and inspections.
If a malfunction occurs, the device should be disconnected and handed over to the
manufacturer for repair.
In order to minimize the risk of malfunction and associated risks to staff, the device
is not to be installed or used in particularly unfavourable conditions, where the fol-
lowing hazards occur:
-possible mechanical impacts, excessive shocks and vibration;
-excessive temperature fluctuation;
-water vapour condensation, dusting, icing.
Changes made to the manufacturing of products may be introduced before the paper version of the
manual is updated. The up-to-date manuals are available on the manufacturer's website:
www.aplisens.com.

EN.IO.LI.24.L.G.SFT
4 Revision 02.A.004/2021.08
TABLE OF CONTENTS
1. INTRODUCTION ......................................................................................... 6
1.1. Purpose of the document.......................................................................................................6
1.2. Registered trademarks...........................................................................................................6
1.3. Definitions and abbreviations.................................................................................................6
1.4. Transmitter set range.............................................................................................................7
2. SAFETY ...................................................................................................... 8
3. TRANSPORT AND STORAGE ................................................................... 9
3.1. Delivery check.......................................................................................................................9
3.2. Transport...............................................................................................................................9
3.3. Storage..................................................................................................................................9
4. GUARANTEE.............................................................................................. 9
5. IDENTIFICATION...................................................................................... 10
5.1. Manufacturer's address .......................................................................................................10
5.2. Transmitter identification......................................................................................................10
5.3. CE mark, declaration of conformity......................................................................................10
6. INSTALLATION ........................................................................................ 11
6.1. General recommendations...................................................................................................11
6.1.1. Installation of rail-mounted transmitter LI-24L Safety on a DIN rail...............................11
6.1.2. Installation of head-mounted transmitter LI-24G Safety in the housing.........................12
7. ELECTRICAL CONNECTION ................................................................... 14
7.1. Cable connection to transmitter terminals............................................................................14
7.1.1. Options for connecting sensors, potentiometers and voltage sources to the transmitter15
7.1.2. Connection of transmitters with the option of using local HART communication...........16
7.2. Transmitter power supply.....................................................................................................17
7.2.1. Transmitter supply voltage ...........................................................................................17
7.2.2. Specifications of electrical switching terminals .............................................................17
7.2.3. Resistance load in power supply line............................................................................17
7.2.4. Shielding, equipotential bonding...................................................................................17
7.3. Final inspection of cabling....................................................................................................17
8. START-UP ................................................................................................ 18
8.1. Alarm configuration..............................................................................................................18
8.2. Configuration of the operating mode....................................................................................20
8.3. Metrological parameters, types of sensors, measuring ranges and errors............................21
9. OPERATION ............................................................................................. 24
9.1. Operating temperature.........................................................................................................24
9.2. Remote configuration of setpoints (HART)...........................................................................24
9.2.1. Compatible devices......................................................................................................24
9.2.2. Compatible configuration software ...............................................................................24
9.2.3. Method of connecting communication devices .............................................................24
10.MAINTENANCE ........................................................................................ 25
10.1. Periodic inspections.............................................................................................................25
10.2. Non-periodic inspections......................................................................................................25
10.3. Spare parts..........................................................................................................................25
10.4. Repair..................................................................................................................................25
10.5. Returns................................................................................................................................25
11.SCRAPPING, DISPOSAL ......................................................................... 26
12.HISTORY OF REVISIONS......................................................................... 26

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 5
LIST OF FIGURES
Figure 1. Set range and measurement limits.......................................................................................7
Figure 2. Warning plate - protective seal.............................................................................................8
Figure 3. Examples of LI-24G Safety transmitter nameplates in standard and Exi version ................10
Figure 4. Examples of LI-24L Safety transmitter nameplates in standard and Exi version.................10
Figure 5. LI-24L Safety transmitter installation on a DIN rail..............................................................11
Figure 6. Installation of the LI-24G Safety transmitter in an example enclosure manufactured by
Aplisens.............................................................................................................................................12
Figure 7. Fastening screw lock protection in the LI-24G Safety transmitter .......................................13
Figure 8. Markings of LI-24L Safety transmitter terminals..................................................................14
Figure 9. Markings of LI-24G Safety transmitter terminals.................................................................14
Figure 10. Methods of connecting sensors, potentiometers and voltage sources..............................15
Figure 11. Electrical connection 4 …20 mA of HART to transmitters in standard version.................16
Figure 12. Electrical connection 4 …20 mA of HART to transmitters in Exi version..........................16
Figure 13. Set range current, saturation currents, alarm currents......................................................18
Figure 14. LED indicator on the LI-24L Safety transmitter.................................................................19
LIST OF TABLES
Table 1. Definitions and abbreviations.................................................................................................6
Table 2. Permissible transmitter supply voltages...............................................................................17
Table 3. Metrological parameters of RTD sensors.............................................................................21
Table 4. Metrological parameters of thermocouples ..........................................................................22
Table 5. Types of measurements, linearization and mathematical operations ...................................23

EN.IO.LI.24.L.G.SFT
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1. INTRODUCTION
1.1. Purpose of the document
The subject of manual are rail-mounted smart temperature transmitters LI-24L Safety and head-
mounted smart temperature transmitters LI-24G Safety, hereinafter referred jointly to as
LI-24L(G) Safety. The manual applies to the following versions: standard and intrinsically safe Exi.
The manual contains data, tips and general recommendations for safe installation and operation of the
transmitters, as well as troubleshooting in case of possible failure.
The manual does not cover explosion protection issues.
Reading the SIL EN.IB.LI.24.L.G.SFT safety manual is mandatory, as it contains detailed
data about the transmitter operation in the functional safety loop.
The use of the equipment in hazardous zones without appropriate approvals is forbidden.
It is mandatory to read EN.IX.LI.24.L.G Explosion-proof Device User Manual, containing
important information related to the installation of intrinsically safe version of the transmit-
ters.
1.2. Registered trademarks
HART®is a registered trademark of FieldComm Group.
Windows®is a registered trademark of Microsoft Corporation.
Google Play®is a service registered and managed by Google®Inc.
1.3. Definitions and abbreviations
Table 1. Definitions and abbreviations
Item
no.
Abbr.
Meaning
1
LRV
“Lower Range Value” – the value of the set range expressed in the units of temperature, re-
sistance or voltage corresponding to the current of 4,000 mA, i.e. 0% of the output setpoint. The
set range must not exceed limits which depend on the selected measurement type. The mini-
mum width of the set voltage range |(URV-LRV)| is limited by software to 10°C for resistive
sensors (10 Ω for resistance measurement) or 50°C for voltage type sensors (50 mV for voltage
measurement).
2
URV
“Upper Range Value” –the value of the set range expressed in the units of temperature, re-
sistance or voltages corresponding to the current of 20,000 mA, i.e. 100% of the output setpoint.
The set range must not exceed the set range limits which depend on the selected measurement
type. The minimum width of the set voltage range |(URV-LRV)| is limited by software to 10°C for
resistive sensors (10 Ω for resistance measurement) or 50°C for voltage type sensors (50 mV
for voltage measurement).
3
LRL
LSL
“Lower Range Limit” or “Lower Sensor Limit” –the lower limit of the set range expressed in the
units of temperature, resistance or voltage. Value (URL-LRL) or (USL-LSL) is referred to as the
transmitter base range and depends on the selected measurement type.
4
URL
USL
“Upper Range Limit” or “Upper Sensor Limit” – the upper limit of the set range expressed in the
units of temperature, resistance or voltage. Value (URL-LRL) or (USL-LSL) is referred to as the
transmitter base range and depends on the selected measurement type.
5
LPL
“Lower Processing Limit” – the lower limit of digital processing of the measured value. The trans-
mitter digitally processes the measurement below the lower limit of the LRL/LSL set range.
When LPL is reached, the transmitter freezes digital value measurement refreshing and the
diagnostic alarm mode I_AL < 3,600 mA is activated. In addition, collective statuses of the trans-
mitter will be set: “Sensor error”, “First Process Variable Calculation Error”, “First Process Vari-
able out of Range” and “Second or Subsequent Process Variables out of Range”. These can be
read out in the diagnostic tab via the HART communication.
6
UPL
“Upper Processing Limit” – the upper limit of digital processing of the measured value. The trans-
mitter digitally processes the measurement up to the upper limit of the URL/USL set range.
When UPL is reached, the transmitter freezes digital value measurement refreshing and the
diagnostic alarm mode I_AL < 3,600 mA is activated. In addition, collective statuses of the trans-
mitter will be set: “Sensor error”, “First Process Variable Calculation Error”, “First Process Vari-
able out of Range” and “Second or Subsequent Process Variables out of Range”. These can be
read out in the diagnostic tab via the HART communication.

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 7
1.4. Transmitter set range
The figure below shows the transmitter LRV/URV set range, limits related to the LRL/URL permissible
set range, LPL/UPL digital processing range of the A/D measuring transmitter. As standard, current
values of 4 mA / 20 mA are assigned to LRV/URV points. In order to obtain reverse characteristics, it
is possible to reverse the assignment so that the LRV/URV points are assigned to 20 mA / 4 mA cur-
rents.
Figure 1. Set range and measurement limits

EN.IO.LI.24.L.G.SFT
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2. SAFETY
−The installation and start-up of the device and any activities related to operation shall
be carried out after thorough examination of the contents of user’s manual and the
instructions related thereto.
−Installation and maintenance should be carried out by qualified staff having the re-
quired authorizations to install electrical and measuring devices.
−The device shall be used according to its intended purpose in line with the permissible
parameters specified on the nameplate (➔5.2. Transmitter identification).
−The protection elements used by the manufacturer to ensure transmitter safety may
be less effective if the device is operated in a manner not consistent with its intended
purpose.
−Before installing or disassembling the device, it is absolutely necessary to disconnect
it from the power source.
−No repairs or alterations to the transmitter electronic system are permitted. Assess-
ment of damages and possible repair may only be performed by the manufacturer or
authorized representative.
−Do not use instruments if damaged. In case of malfunction, the device must be put out
of operation.
−It is not allowed to tear or damage the protective seal on the housing.
Figure 2. Warning plate - protective seal

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 9
3. TRANSPORT AND STORAGE
3.1. Delivery check
After receiving the delivery of the equipment, it is necessary to:
-make sure that the packaging and its contents were not damaged during transport;
-check the completeness and correctness of the received order, and make sure no parts are
missing.
3.2. Transport
Transport of transmitters shall be carried out with the use of covered means of transport, in original
packages. The packaging shall be protected against movement and direct impact of atmospheric fac-
tors.
3.3. Storage
Transmitters shall be stored in a factory packaging, in a room without vapours and aggressive sub-
stances, protected against mechanical impact.
Allowable range of storage temperature:
-40 …85°C (-40 …185°F).
4. GUARANTEE
General terms and conditions of guarantee are available on the manufacturer’s website:
www.aplisens.com/ogolne_warunki_gwarancji.
The guarantee shall be repealed if the device is used against its intended use, failure to
comply with user’s manual or interference with the structure of the device.

EN.IO.LI.24.L.G.SFT
10 Revision 02.A.004/2021.08
5. IDENTIFICATION
5.1. Manufacturer's address
APLISENS S.A.
03-192 Warsaw
Morelowa 7 St
Poland
5.2. Transmitter identification
Depending on the version of the transmitter, the nameplates may differ in the amount of information
and parameters.
Figure 3. Examples of LI-24G Safety transmitter nameplates in standard and Exi version
Figure 4. Examples of LI-24L Safety transmitter nameplates in standard and Exi version
1. Logo and name of the manufacturer.
2. Transmitter type.
3. CE mark.
4. Product QR code.
5. Transmitter model ID.
6. Types of measuring inputs.
7. Supply voltage values.
8. Permissible range of ambient temperature.
9. Output signal.
10. Note about the obligation to read the manual.
11. Transmitter serial number.
12. Year of manufacture.
13. Designation of the explosion-proof type, certificate designation in case of ATEX certified transmitters.
14. Intrinsic safety parameters, i.e.: Ui, Ii, Pi, Li, Ci, Uo, Io, Po, Co, Lo.
15. Number of the notified body for transmitters with ATEX certificate.
5.3. CE mark, declaration of conformity
The device has been designed to meet the highest safety standards, has been tested and has left the
factory in a condition that is safe for operation. The device complies with the applicable standards and
regulations listed in the EU Declaration of Conformity and has CE marking on nameplate.

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 11
6. INSTALLATION
6.1. General recommendations
It is recommended to install the transmitters in closed enclosures in order to ensure pro-
tection against environmental factors.
6.1.1. Installation of rail-mounted transmitter LI-24L Safety on a DIN rail
Figure 5. LI-24L Safety transmitter installation on a DIN rail
1. Rail-mounted transmitter LI-24L Safety.
2. Movable clip.
3. DIN 35 rail.
Insert the movable clip (2) of the LI-24L Safety transmitter housing (1) over the DIN rail (3). Then press
the transmitter (1) towards the rail (3). Ensure that the movable clip (2) is clamped on the rail (3). To
remove the transmitter, pull the movable clip (2) out with a flat-end screwdriver (put the screwdriver
through the clip lug (2)) and slide the transmitter (1) off the rail (3).

EN.IO.LI.24.L.G.SFT
12 Revision 02.A.004/2021.08
6.1.2. Installation of head-mounted transmitter LI-24G Safety in the housing
1. Housing cover.
2. Cover gasket.
3. Fastening screws.
4. Head-mounted transmitter LI-24G Safety.
5. Insulating washer.
6. Measuring unit.
7. Housing.
8. Sensing element protective tube.
Pull the connection cables of the measuring unit (6)
through the centre hole of the insulating washer (5) and
then through the centre hole of the head-mounted trans-
mitter (4).
Screw the fastening screws with the mounted springs (3)
into the transmitter mounting holes (4) and insert them
through the holes in the insulating washer (5) and the
measuring unit (6).
Mount the head-mounted transmitter (4) together with
the insulating washer (5) and the measuring unit (6) to
the housing (7) using the fastening screws with mounted
springs (3).
Connect the connection cables of the measuring unit (6)
to the measuring terminals of the head-mounted trans-
mitter (4) according to section 0 of user’s manual.
Unscrew the cable gland, pull the power cable through
the cable gland opening into the housing (7). Connect
the power supply cables according to section ➔7.1. Ca-
ble connection to transmitter terminals of user’s manual
to the power terminals of the head-mounted transmitter
(4). Gently pull outthe excess cableand tighten the cable
gland.
Screw the housing cover (1) together with the gasket (2)
onto the housing (7).
Screw in the protective tube of the measuring unit (8).
Figure 6. Installation of the LI-24G Safety transmitter in an example enclosure manufactured by Aplisens

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 13
The head-mounted transmitter LI-24G Safety is equipped with fastening screw lock protection in the
form of locks in the mounting holes. The lock is suitable for use with screw threads, and therefore the
screws must be screwed into the transmitter housing.
Pushing the fastening screws into the mounting holes instead of screwing them in may
damage the screw lock protection.
Figure 7. Fastening screw lock protection in the LI-24G Safety transmitter

EN.IO.LI.24.L.G.SFT
14 Revision 02.A.004/2021.08
7. ELECTRICAL CONNECTION
All connection and installation operations must be performed with disconnected supply
voltage and other external voltages, if used.
Failure to provide proper connection of the transmitter may result in danger.
Risk of electric shock and/or ignition in potentially explosive atmospheres.
7.1. Cable connection to transmitter terminals
In the LI-24L(G) Safety transmitter, the 4 …20 mA current loop power supply and signal cables must
be connected to respective “+” and “-” terminals.
In order to perform correct connection of the cables, the following steps shall be performed:
−disconnect power supply;
−connect the transmitter in accordance with figures below and section ➔7.1.1. Options for con-
necting sensors, potentiometers and voltage sources to the transmitter, paying attention to the
correct tightening of the screws fixing the conductor core to the terminal;
−depending on the assumed earthing model of the system, attach the cable screen to the bolted
terminal of thebody ground or cut the excess of the screen and secure with the insulationwithout
connecting to the body ground (applies to LI-24G Safety in housing).
Figure 8. Markings of LI-24L Safety transmitter terminals
Figure 9. Markings of LI-24G Safety transmitter terminals

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 15
7.1.1. Options for connecting sensors, potentiometers and voltage sources to the transmit-
ter
Figure 10.Methods of connecting sensors, potentiometers and voltage sources

EN.IO.LI.24.L.G.SFT
16 Revision 02.A.004/2021.08
7.1.2. Connection of transmitters with the option of using local HART communication
The method of connecting a modem to transmitterfor local HART communication is shown in the figures
below.
In order to communicate using locally connected HART modem to the transmitter ”+”and
“-“terminals, make sure that the ROresistance viewed from the side of transmitter termi-
nals towards power source is in the range of 240 Ω ≤RO≤1100 Ω.
Figure 11.Electrical connection 4 …20 mA of HART to transmitters in standard version
Figure 12.Electrical connection 4 …20 mA of HART to transmitters in Exi version
It is mandatory to read EN.IX.LI.24.L.G Explosion-proof Device User Manual, containing
important information related to the installation of transmitters in intrinsically safe ver-
sion.
The converter may also be operated using Aplisens Mobile Configurator installed on smartphones
with Android system and connected using wireless communication.
The software is available on Google Play®:
https://play.google.com/store/apps/details?id=com.aplisens.mobile.amc.

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 17
7.2. Transmitter power supply
7.2.1. Transmitter supply voltage
Power cables may be live.
In case of incorrect connection there is a risk of electric shock and/or explosion.
Installation of the transmitter in explosion-risk atmospheres must comply with the require-
ments of relevant instructions and national standards and regulations.
All explosion protection data is given in manual EN.IX.LI.24.L.G.
Table 2. Permissible transmitter supply voltages
Version
Minimum supply voltage
Maximum supply voltage
Standard
10 V DC
36 V DC
Exi*
10 V DC
30 V DC
*For details on the intrinsically safe version, see manual EN.IX.LI.24.L.G.
7.2.2. Specifications of electrical switching terminals
Electrical switching terminals are suitable for conductors with the cross-section area of:
-for LI-24L Safety: ≤2,5 mm2;
-for LI-24G Safety: ≤1,75 mm2.
Possible cables to be used:
-unshielded when using the analogue signal only;
-shielded, approved for the HART communication;
-shielded on the sensor(s) side for a cable length greater than 30 m.
7.2.3. Resistance load in power supply line
The power line resistance, power source resistance and other additional resistances connected in se-
ries increase the voltage drops between the power source and the transmitter terminals. The maximum
transmitter current under normal operation conditions is defined as I_max = 20,500 mA + E, where E is
the permissible safe error equal to ± 0,320 mA.
The maximum resistance value in the power circuit (along with the power cables resistances) is defined
by the formula:
󰇟󰇠󰇛󰇜󰇟󰇠
󰇟󰇠
where:
U –voltage at the supply terminals of 4 …20 mA current loop [V].
RL_MAX –maximum power line resistance [Ω].
7.2.4. Shielding, equipotential bonding
Optimal protection against interference is provided by the earthing of the screen on both sides (in the
cabinet and equipment). In case of potential difference between earthing points of devices which may
result in the flow of equipotential currents, the screen shall be earthed on one side.
7.3. Final inspection of cabling
After completing the electrical installation of the transmitter, it is necessary to check the following:
-does the supply voltage measured at the transmitter terminals at maximum set current match
the range of supply voltage specified on the transmitter nameplate?
-Is the transmitter connected according to the information given in section ➔7.1. Cable connec-
tion to transmitter terminals?
-Are all the screws tightened?
-Are the cable terminals tightened?
-Is the cable gland tightened?

EN.IO.LI.24.L.G.SFT
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8. START-UP
Upon request, the customer receives a transmitter configured according to the setpoints specified in
the order.
The current base range and the basic unit of the transmitter can be read out from the device via the
HART communication.
8.1. Alarm configuration
The LI-24L(G) Safety transmitter features an advanced internal diagnostics resulting from the require-
ments of PN-EN 61508 standard. The internal diagnostics of the transmitter monitors the operation of
its electronic circuits, process parameters and environmental parameters, thus ensuring an increased
level of functional safety. Diagnosed dangerous conditions or malfunctions of the internal transmitter
systems result insetting alarm current I_AL < 3,600 mA. The user cannot disable diagnostics or change
the alarm current value. The figure below shows the normal operation ranges of the transmitter process
output as well as saturation and alarm current ranges.
Figure 13.Set range current, saturation currents, alarm currents
1 –Set 4 …20 mA current area corresponding to setpoint 0 …100% of the process output.
2 –Lower saturation current of 3,900 mA.
3 –Upper saturation current of 20,500 mA.
4 –Alarm current area I_AL < 3,600 mA for internal diagnostic alarms.
5 –Alarm current area I_AL > 20,820 mA for alarms related to safe failures with external diagnostics.
Temperature transmitters LI-24L(G) Safety manufactured by Aplisens meet the alarm re-
quirements of Namur NE 89 and Namur NE 43.
The transmitter diagnostics continually tests the environmental parameters:
-Temperature of the ADC transducer converting the electric signal from the temperature sensor
to the digital value of measurement.
-Temperature of the CPU unit (transmitter’s main microcontroller). If the transmitter operating
temperature limits are exceeded, the diagnostics will trigger alarm I_AL < 3,600 mA. Tempera-
ture return to permissible operating range of the transmitter will result in deactivation of the
diagnostic alarm mode and restoration of normal operation.

EN.IO.LI.24.L.G.SFT
Revision 02.A.004/2021.08 19
The transmitter diagnostics continually tests the process parameters of temperature:
-If the measured process variable value increases above the upper value of the base range
relative to URL, when UPL is reached, the diagnostics will trigger alarm I_AL < 3,600 mA. Tem-
perature return below UPL point will result in deactivation of the alarm and restoration of the
transmitter to its normal operation.
-If the measured process variable value decreases below the lower value of the base range
relative to LRL, when LRL is reached, the diagnostics will trigger alarm I_AL < 3,600 mA. Tem-
perature return above the LPL point will result in deactivation of the alarm and restoration of the
transmitter to its normal operation.
The transmitter diagnostics continually tests electric parameters and software resources of the
transmitter:
-If the internal diagnostics detects malfunctions or failures of the transmitter that are not critical
for integrity of hardware and software, the transmitter software will trigger alarm
I_AL < 3,600 mA. The diagnostic alarm state will continue until the malfunction or failure is
resolved. The LED indicating the operating status of the device will indicate improper operation
to attract the operator's attention. The transmitter will set the current output to the alarm state
I_AL < 3,600 mA.
-If the internal diagnostics detects 20 unauthorised access attempts to write operation or pass-
word change protection codes, the transmitter will set the current output to alarm
I_AL < 3,600 mA. This state will continue to exist until the transmitter softwarereset is performed
or until power supply is disconnected and then re-connected.
Critical diagnostics:
-It detects RAM, FLASH, CPU errors and current mismatch in the current loop in alarm mode.
The detected errors stop internalSIL watchdog refreshing, disable the internal transmitter power
supply and trigger alarm current I_AL << 3,600 mA (rated I_AL < 0,300 mA). To restore the
operation of the transmitter after a critical alarm, it is required to disconnect the transmitter from
its power supply temporarily at the terminals and then re-connect it. The occurrence of
a critical alarm with correct power supply parameters at the transmitter terminals usually indi-
cates a serious malfunction of the transmitter.
The design of the transmitter allows detection of many dangerous failures. In addition to the diagnostics
signalled with alarm current I_AL < 3.600 mA and the diagnostics being readable by via digital HART
communication, the LI-24L Safety transmitter is equipped with a two-colour LED indicator which signals
the operating status of the device.
Description of displayed prompts:
-green –correct operating status;
-red –hardware failure;
-flashing red –missing or incorrect connection of RTD/TC sensor, exceeded ambient tempera-
tures, excessive drift of reference voltages;
-LED indicator OFF –critical alarm (the transmitter disconnects from power supply).
Figure 14.LED indicator on the LI-24L Safety transmitter

EN.IO.LI.24.L.G.SFT
20 Revision 02.A.004/2021.08
8.2. Configuration of the operating mode
Before starting the work with the transmitter, the following parameters must be configured:
-basic unit of the transmitter process variable;
-measurement input type (voltage/resistance);
-measurement sensor processing characteristics (selection of sensor linearization characteris-
tics);
-measurement sensitivity range (100 mV / 1000 mV or 400 Ω / 2000 Ω);
-type of sensor connections, number of terminals, CJC configuration (internal, external or none);
-type of the mathematical function processing the signal from two sensors (2 x RTD 2-wire con-
nection, 2 x RTD 3-wire connection, 2 x thermocouple, 2 x thermocouple with external CJC (see
➔Figure 10. Methods of connecting sensors, potentiometers and voltage sources)):
-difference of measurements from channels: Ch1-Ch2 or Ch2-Ch1;
-measurement average: 0,5 (Ch1+Ch2);
-minimum value of the two measurements: min (Ch1, Ch2);
-maximum value of the two measurements: max (Ch1, Ch2).
In case of using the configuration with linearization, shorting one of the sensors results in trig-
gering an alarm. This is due to the measurement going beyond the linearization table. In non-
linearization configurations with resistance sensors, short circuits are undetectable;
-additional parameters such as offset of measuring channels or compensation of sensor lead
resistance;
-start point of the set LRV range in the basic unit;
-end point of the set URV range in the basic unit;
-damping time constant;
-analogue output processing characteristic mode;
-transmitter tag (TAG);
-setting of the password for the settings change lock;
-setting of the write lock after performing the configuration actions.