LTL2000S / SQ RETROREFLECTOMETER
Manual
DELTA ??? Venlighedsvej 4 ???
LTL2000S / SQ RETROREFLECTOMETER
Manual
DELTA ??? Venlighedsvej 4 ???
DISCLAIMER
The information contained in this document is subject to change without notice.
DELTA LIGHT & OPTICS MAKES NO
WARRANTY OF ANY KIND WITH RE-
GARD TO THIS MATERIAL, INCLUD-
ING, BUT NOT LIMITED TO, THE IM-
PLIED WARRANTIES OF MERCHAN-
TABILITY AND FITNESS FOR A PAR-
TICULAR PURPOSE. DELTA LIGHT &
OPTICS SHALL NOT BE LIABLE FOR
ERRORS CONTAINED HEREIN OR FOR
INCIDENTAL OR CONSEQUENTIAL
DAMAGES IN CONNECTION WITH THE
FURNISHING, PERFORMANCE OR USE
OF THIS MATERIAL.
Rev. 080104
SW ver: 1.6
i
iii
SECTION 1
INTRODUCTION
Introduction
This manual covers both LTL2000S and LTL2000SQ. Some functions will only be available on LTL2000SQ and will be printed in blue colour.
The LTL2000S is a portable field instrument, intended for measuring the reflection properties of road markings ???Rl??? as seen in the vehicle headlight illumination.
To measure the Rl properties (coefficient of retro reflected luminance) the road is illuminated at an angle of 1.24 deg. and the reflected light is measured at an angle of 2.29 deg.
The LTL2000SQ is intended for measuring both ???Rl??? and the lightness of road surfaces and road markings ???Qd??? as seen under daylight conditions or with stationary lighting.
To measure the Qd properties (the luminance coefficient under diffuse illumination) the road is illuminated with a diffuse source and the reflected light is again measured at an angle of 2.29 deg.
An observation angle of 2.29 deg corresponds to an observational distance of 30 metre, thus relevant for a motorist viewing situation under normal driving conditions.
Rl and Qd is important factors in the
LTL2000SQ
LTL2000S
The operation of the instrument is very simple and requires a minimum of instruction. An er- ror message or warning is given in case of unreliable or erroneous measurement.
The LTL2000S(Q) measures the Rl and Qd values according to international agreements. Re- sults are presented in plain English on a LCD display. The
Serial communication on RS232 port gives extended command, calibration, diagnostics and data dump facilities.
The LTL2000S(Q) is powered by a rechargeable lead acid battery, giving several hours of measurement capacity. A mains powered battery charger is supplied as standard.
LTL2000S(Q) features
???Portable
???Measurement in full daylight
???Automatic stray light compensation and error diagnostics
???Dry and wet surfaces
???Plane, textured & profiled markings
???Measurement geometry and illumination corresponding to realistic viewing condition in traffic
???Direct digital read out
???Automatic mean calculation
???
???Real time clock
???Automatic data storage in internal
???RS232 serial communication for operation, data dump, extended control and di- agnostics
???Automatic programmable power off function
???Easy calibration procedure
???Calibration unit
???Carrying case
Getting started
Buttons
Measuring
Turn the instrument on by pressing and holding the 
button until the LCD shows:
Calibrate the instrument if necessary, see Calibration page 6.
Place the instrument on the road marking. Press the 
key.
The measurement will start instantly. Duration approx. 3 sec. depending on measurement mode (approx. 5. sec when measuring both Rl and Qd).
When finished the measured Rl (and Qd) values, the date/time or measurement id and status info is displayed. The information???s are automatically transferred to the internal data log for later readout to the serial communication port or printout.
The instrument can automatically calculate and display the mean (average) value of 2 or more measurements, if the Mean Calc function is ON. See Menu system.
Warning and Errors
Warning and errors are indicated in the lower right positions in the second line of the display:
If the error indicator is different from * then press 
to 
one or more times to select Status Display and then use 
to
scroll through the status list to see the possible cause of the problem. For further description on the error messages see Status Display page 19. Alternatively or select the menu Print Status to print a complete instrument status.
Note:
When battery voltage becomes low a warning (W) is shown in the lower right corner of display. It is still possible to take measurements but when the voltage drops too low, readings can be erroneous.
If in doubt whether the readings are correct make a control measurement on the calibration unit.
Wet night measurement considerations:
Making wet night measurements on warm road surfaces requires special considerations.
Due to the large thermal mass of the road, the road temperature is not influenced very much by the water.
Pouring water on the hot road surface will generate steam. When placing the instrument on the wet road steam will condense in the instrument also on the front window.
Condense on the optical surfaces will result in measure error!
Tests has shown that steam especially condensate on the outside surface of the front window. When removing the instrument from the road, the dew will evaporate quickly and the instru- ment will again take correct readings.
It is recommended to make the "wet measurements" at the lowest possible road temperature!
Print Result: 
Press 
to print the result from last calibration or measurement to the printer.
Menu: 
Press this key to enter the menu section. Press 
again to scroll through the menu structure.
From the Menu it is possible to control most of the instrument settings such as mean calcula- tion, data log functions, real time setup and automatic turn off timer, see Menu system page 21.
The measuring mode (Qd, Rl or both) is set using this key.
The sequence of the menu functions changes depending on what mode the instrument is in at the moment. Example: when taking measurements with the mean calculation on the first func- tion shown will be the Clear Mean function.
Home: 
Press this key to terminate a menu or calibration and display the latest measurement result, if
the Mean calculation function is enabled and there is more than 1 measurement in the calcula- tion then the number of measurements is shown first.
Scroll Keys: 
In normal mode the 
key activates the Clear Top Log function, in menu mode it is used to scroll through the menu functions and to increment shown values.
In normal mode the 
key activates the Edit Sequence Id function, in menu mode it is used to scroll through menu functions and to decrement shown values.
For more information about the keyboard buttons please see page 19.
Calibration - LTL2000S
A calibration should always be carried out before starting a new series of measurements.
Calibration is done by placing the calibration unit underneath the instrument between the rails. The easiest way to place the unit is to tilt the instrument backwards.
Figure 1. How to tilt the instrument.
The calibration units are fitted with guidance pins on the outside. The pins mounted in the middle of the longitudinal direction of the unit shall fit in the notch in the rails.
The instrument automatically compensates for zero signal, leakage and other possible error sources, and calculates the calibration factor. This process is fully automatic and if the cali- bration routine is followed precisely the retroreflectometer will now measure ???true??? Rl.
Rl Calibration
Rl calibration step 1 to 8 actually consists of two calibrations: a ???zero calibration??? and a ???normal calibration???. The zero calibration is done on the calibrator light trap and the normal calibration on the ceramics. It is important to turn the Rl calibration unit the right way during the calibration sequence. See figure 2 (page 9).
Press the 
key to enter calibration mode and follow the instructions in the display.
Note:
Step 1 + 4: See figure 2 on how to place the calibration unit.
Step 2: The message will be shown for a couple of seconds.
Step 3: The message will be shown briefly.
Step 5: The message will be shown for a couple of seconds.
Step 6: Edit the Rl Normal value according to the value printed on the calibration unit.
Step 7: Accept the shown normal value.
To verify the calibration do a Rl measurement on the normal before removing the normal in step 8.
To document the calibration press the 
key to print.
In the example above the Rl function is now calibrated to a Rl value of 150.
If an error is detected during the calibration procedure then the display will indicate this.
Note:
???Avoid calibration in direct sunlight
???Store the reference calibration unit in a dry and clean environment.
Calibration - LTL2000SQ
A calibration should always be carried out before starting a new series of measurements.
The LTL2000SQ is supplied with two calibration units. One for Rl and one for Qd.
The order of R1 / Qd calibration is not critical. Qd calibration can be done before the Rl cali- bration and reverse. The Rl / Qd calibration can also be performed individually.
The Qd calibration only consist of one calibration (no zero calibration is needed).
Calibration is done by placing the calibration unit underneath the instrument between the rails. The easiest way to place the unit is to tilt the instrument backwards, see picture page 6. The calibration units are fitted with guidance pins on the outside. The pins mounted in the middle of the longitudinal direction of the unit shall fit in the notch in the rails, see figure 2 page 9.
The instrument automatically compensates for zero signal, leakage and other possible error sources, and calculates the calibration factor. This process is fully automatic and if the cali- bration routine is followed precisely the retroreflectometer will now measure ???true??? Rl / Qd.
Calibrate:
Press the 
key to enter calibration mode.
If only Rl or Qd mode is enabled then this mode is the only one shown. In the example both Qd and Rl are enabled.
The display will show:
Calibration
= Qd 
= Rl
Use 
or 
key to activate the wanted calibration sequence.
Qd Calibration:
Follow the instructions in the display.
Note:
Step 1: The vertical black plate on the calibration unit shall face forward (see figure 2 page 9).
Step 2: The message will be shown for a couple of seconds.
Step 3: Edit the Qd Normal value according to the value printed on the calibration unit.
If the 
key is pressed the calibration result is printed.
In the example above the Qd function is now calibrated to a Qd value of 215. If an error is detected during the calibration procedure then the display will indicate this.
Rl Calibration:
See Rl calibration page 6.
Zero calibration for the Rl calibration (step 1 in the detailed de- scription page 5).
Rl calibration (step 4 in the detailed de- scription page 5)
Qd calibration (step 1 in the detailed de- scription page 6.)
Rail
Guidance pin placed in notch
The normal must be placed with this side up for the different calibrations.
Guidance pins
Figure 2. How to place the calibration normals.
Remember:
??Recharge battery when possible. Never leave battery discharged for longer periods of time.
??Keep protection window, light trap and calibration unit clean.
??LTL2000S(Q) is an optical precision instrument, handle with care.
??Store in clean and dry environment
SECTION 2
GENERAL INFORMATION
Rl Measurement
The Rl part of the LTL2000S(Q) Retroreflectometer measures the Rl (coefficient of retro re- flected luminance) parameter. The Rl parameter represents the brightness of the road mark- ings seen by drivers of motor vehicles by headlight illumination.
The illumination angle is 1.24?? and the observation angle is 2.29?????simulating a drivers view- ing distance of 30 metres at an eye height of 1.2 metres. The observation area is app. 45 mm. x 200 mm.
The optical specification complies with EN1436. The spectral sensitivity is eye matched us- ing SMART optical filter designed and produced by DELTA. The functional layout of the LTL2000S(Q) Rl optical system is shown in figure 3 below.
A very efficient electronic stray light compensation eliminates false signals from daylight.
101 Light source
102 Receiver and spectral matching filter
103 Illumination aperture stop
104 Observation aperture stop
105 Illumination beam
106 Observation beam
107 Collimating lens
108Mirror
109Beam splitter
110Road marking surface
111Illumination field
112Observation field
107
Figure 3: LTL2000S(Q) RL optical system layout
The illuminations field with a length of 200mm length and 43 mm wide gives a large measur- ing measurement field of 85 cm2. Combined with an observation field of 350 mm length this gives a considerable capability to measure profiled and textures makings but also a high reli- ability for obtaining correct readings for un even surfaces or if small debris are present at one of the instruments support pads on the marking.
Because of illumination at an angle of only 1,24?? to the surface in the
Refer to figure 3 for results of the measurements. The RL value is roughly constant up to the height of 4 mm, but at 5 mm there is some reduction.
To understand this, one needs to know that the illuminated patch moves by 46 mm per mm, but the measurement area by only 25 mm per mm at the measuring angle of 2,29?? relative to the surface (1 mm/sin 2,29?? = 25 mm). The measuring area is larger than the illuminated patch, and contains it, but at some lift the illuminated patch moves partly out of the measured area - causing reduction of the measured RL value.
On the basis of these measurements, it can be claimed that this particular instrument has a reach of almost 5 mm down into a profiled road marking, and the corresponding 5???46 mm = 23 cm reach along gaps. This reach is assumed to be 20 cm to be on the safe side.
The significance is that the instrument can readily be used to measure the RL of profiled road markings, when the profiles are at most 5 mm high, or gaps between profiles are at most 20 cm. Refer to figure 5 page 14.
In practice, it is necessary to take readings at a number of positions covering one or more pro- files. There may be variation with the position, but the average value will reflect the true RL value of the profiled road marking as experienced by a driver at night.
Most of profiled road markings used on roads in Europe can be measured with the LTL 2000S(Q), and are in fact measured with the LTL2000 as a matter of routine. Examples are 'Spotflex', Longflex', 'Rainline' and
FOR MARKINGS EXCEEDING 5 MM HEIGHT/200 MM IN SPACING PLEASE
CONTACT DELTA.
Figure 4: Simulation of profiled markings and/or
up to 5 mm profile height
up to 20 cm profile gap
Figure 5: The reach of the LTL 2000S(Q) makes it capable of measuring profiled road markings of profile height up to 5 mm, or profile gap up to 20 cm.
The advantage of the DELTA optical arrangement with a smaller illumination field in a large measurement field is illustrated in the figure 6 below compared to a system with two identical fields.
Pro profiled/textures markings, on even markings and in situations where a small debris (e.g. small stone) the instrument is lifted / tilted. The advantage of the LTL2000S(Q) optical ar- rangement is that the measurement still is correct in contrary to other systems available on the market with identical fields where the results obtained are incorrect because the illuminations field is not fully within the measurement field.
Area not measured
Figure 6: The LTL2000S(Q) illuminations/measurement fields ( 5mm profile capabil- ity) compared to a system with identical fields (< 0.5 mm profile capability) clearly shows the advantage of the LTL2000S(Q) for obtaining reliable and reproducible meas- urements on real markings.
Qd Measurement
The Qd part of the LTL2000SQ Retroreflectometer measures the Qd (coefficient of diffuse reflected luminance) parameter. The Qd parameter represents the Lightness of road surfaces and road markings seen by drivers of motor vehicles under daylight conditions or with sta- tionary lighting.
The Qd measurement function of the LTL2000SQ complies with the EN1436 for normal non- glossy road markings with a maximum profile. For measurement on glossy road markings or markings with a profile height exceeding 2 mm please contact DELTA.
The illumination system recommended in EN1436 for obtaining the diffuse illumination for measuring of Qd is an integrating sphere but it is also stated that other illuminations systems can be used if similar results are obtained. The very compact illumination systems in LTL2000SQ is a result of a considerable research effort at DELTA using advanced optical simulation programs. The patent pending illumination system is shown in figure 7. The re- sults obtained with this illumination system is in close agreement with results obtained on Qd measurements using an integrating sphere systems as Qd30 for normal
512
512 Road marking surface
???Light source
???Diffusing box with white interior finish 517 Thin perforated plate
518 Aperture into diffusing box
Figure 7. Qd illumination system
Instrument function
Physically the instrument is dominated by the ???control tower???. The tower contains the Rl il- luminating and observation system and the control electronics.
The unit on top of the base structure contains the Qd illumination system, the observation sys- tem is the same for both Rl and Qd.
The base structure contains an optical system with mirrors that directs Rl illumination beam towards the road surface and the Rl or Qd signal to the detector through a
The instrument is controlled by a microprocessor that executes the measurement automatical- ly by the push of a button and presents the result on a display. The result is automatically transferred to an internal
The LTL2000S(Q) is powered by a
Factory calibration
The LTL2000S(Q) Retroreflectometer is factory calibrated. This calibration is carried out by using calibration units mounted in specially designed frames. The calibration unit's values are measured in the laboratory using traceable methods and equipment.
Notes on error sources
Stray light can enter the instrument between the skirts and the road. Leakage will under nor- mal measurement conditions not be significant. Nevertheless it may occur. Before each meas- urement the LTL2000S(Q) automatically evaluates the leakage and the result is compensated before read out. In case of a significant leakage level a warning or error message is given and special precautions such as screening may be necessary.
Instrument leak, drift and offset errors are compensated by means of data obtained during the calibration procedure. It is very important to keep the light trap, the
The LTL2000S(Q) illumination angle is 1.24?? relative to the road surface. Because of this small angle accurate placement on the road is important. Avoid pebbles and abnormal irregu- larities.
The LTL2000S(Q) must be parallel with and close to the road.
The LTL2000S(Q) Retroreflectometer is a rugged instrument, but it is an optical instrument and must be handled as such.
The LTL2000S(Q) is factory calibrated. Nevertheless start important measurements with a calibration. Study the Retroreflectometer status and error messages if any. See also Section 4
??? Maintenance (page 25).
When the battery voltage becomes low a warning is shown in the display (W). It is still possi- ble to take measurements but when the voltage drops further, readings can be erroneous.
If in doubt whether the readings are correct make a control measurement on the calibration unit.
Note
Keep light trap,
Keep battery fully charged. A well charged battery is more resistant to ageing and damage by freezing
SECTION 3
KEYBOARD, DISPLAY AND FUNCTIONS
Keyboard Layout
. . . . . .
Turns the instrument On. Hold activated until the sign on message appears in the Display.
Turns the instrument Off. Terminates all activity and powers off.
Take a measurement and show the result in the display. All relevant data is automatically stored in the data log for later print or dump to the communication port.
Enter calibration menu. Follow the instructions in the display.
Enter - Activates selected function, accepts changed settings and con- firms choices.
Home (Home position) - Cancels selected function or menu and return to top control level displaying the latest measurement result.
Outputs the latest measurement or calibration result to the printer. Printout has to finish completely before any other function can be se- lected. Printout can only be terminated by turning off the instrument with 
Menu - When in normal operation mode this key activates the menu system and displays the first item in the menu stack. When already in menu mode it selects the next menu item, it is possible to leave the
menu mode entirely at any time with the 
key or by selecting other function keys.
Scroll up - In normal mode the 
key activates the Clear Top Log function. See Clear log data below.
In Menu mode it functions as a scroll or increment function. Values are incremented until they reach their predefined max. limit and then automatically change to their predefined min. limit. The key is auto repeating with increasing repetition rate when held active.
Scroll down - In normal mode the 
key activates the Edit Meas- urement Id (Seq Id) function. See Measurement id below.
In menu mode it functions as a scroll or decrement function. Values are decremented until they reach their predefined min. limit and then automatically change to their predefined max. limit. The key is auto repeating with increasing repetition rate when held active.
Clear log data
Data log entries can be deleted.
Pressing 
in normal mode activates the deletion of the measurement from the top of the data log. The values from the previous measurement will be shown and if a Measurement id was defined for that measurement it will be restored as well.
All log data can be deleted using Menu function Free log. See page 24.
Clearing the top log will reset the mean calculation.
Measurement id
LTL2000S(Q) has a built in function to mark each measurement with a user defined name (sequence id) and a unique sequence number automatic generated by the instrument. The se- quence id and the sequence number will also be stored in the log. The length of the sequence id text is 6 characters.
If any sequence id is defined, the id text and a sequence number are shown in the display.
Entering Measurement id:
To enter / edit the sequence id press the 
button when in home position.
Use the 
button to scroll through the alphabet in direction A..Z (starting with the space character), 0..9. The 
button will scroll through the alphabet in opposite direction.
When the wanted character is shown press the 
button to advance to the next position. You have to step through all 6 positions before the sequence id function will be accepted.
When typing a new sequence id text or editing an old one, the sequence number is reset to 0. When all 6 positions are set to space the sequence id function is undefined and no longer in- cluded in the log nor shown in the display. This can also be done using the Menu command:
Disable Id
Mean Calculation
The instrument automatically calculates and displays the mean (average) value of 2 or more measurements when the Mean Calc function is ON. See Menu system.
If the Rl / Qd value shown in the display contains a decimal point (.) then the shown value is a mean value. The number of samples is displayed for one second after each measurement.
Press 
to redisplay this information.
The following actions will clear the mean calculation:
???Clear Top Log function
???Toggling the Rl / Qd modes
???Clear mean (from menu)
???New calibration
Measurements stored in the log are not the displayed average values but the actual measure- ment value.
If a measurement error occurs (e.g. Rl / Qd out of limit) a message: ???Error! Can???t calc new mean!??? is shown in the display. Both measurements (Rl / Qd) are ignored, a new average is not calculated and the sample number is not incremented. The measurements how ever are stored in the log as normal.
Menu system
Press 
to enter the menu system.
Menu points are:
???Qd Mode
Press 
to toggle Qd mode ON and OFF. When ON the instrument will perform a Qd measurement when 
is pressed.
???Rl Mode
Press 
to toggle Rl mode ON and OFF. When ON the instrument will perform a Rl measurement when 
is pressed.
???Status Display
The results and status recorded during measurement and calibration can be shown in
the display one at a time using the 
keys.
An * after a text means that the message only is shown at special occasions e.g. an er- ror or warning!
???Disable Id
Clear the measurement id.
???Free Log
Shows the numbers of free log positions in the log. Pressing 
will clear the log. In order to avoid accidental erasing the log, a second 
is required.
???Print Log
Output all the data in the log to the printer. Press 
to select.
The display now shows the number of measurements in the data log. Press 
to start printing. The print process continues until all the data has been printed (newest first). The only way to stop is to turn the instrument off.
???Print Status
Output the instrument status to the printer, see page 37.
???Default Settings
Establish the default settings for various programmable values. This enables the user to start over from a default state.
Press 
again to activate this action.
Default values are loaded from the permanent memory. The log data is NOT effected. After default values are loaded the instrument must be calibrated.
???Log Warn
When the data log becomes full a warning can be shown in the display (W). Use 
to toggle Log Warn ON / OFF function.
If off no warning is shown when the log becomes full!
Note: If the log becomes full when Log Warn is ON then the measurement data is no longer stored in the log!
???Off Timer
In order to prolong the operational time of the instrument it has an automatic off func- tion that shuts off the power when no action has been going on for more than a pro- grammable time. The automatic turn off time can be from 60 to 600 seconds or it can be disabled entirely (time < 60 sec.).
???Edit Year (Time and date)
The
Use 
keys to change the Year setting. Press 
to switch to edit Month, edit Date, edit Hour and edit Minute. When the display shows the desired date and time press 
a last time to set the real time clock to the displayed setting
???Mean
Use 
to toggle Mean function ON / OFF. See also page 21.
???Clear Mean (only shown if Mean function is ON) Press 
to reset the Mean calculation.
When the Mean calculation is active Clear mean will be the first menu point.
SECTION 4
MAINTENANCE
General care
The Retroreflectometer is constructed for outdoor use in ordinary good weather conditions. It will stand moist weather with wet roads, but caution must be taken against rain or splashes and dirt from traffic. The LTL2000S(Q) Retroreflectometer is an optical instrument and shall be handled as such. Avoid shock and vibration if possible.
Note
Keep dust/protection window and light trap clean
Protection window
The protection window is located in the optical unit. The protection window is coated with a high efficiency anti reflection coating. Care must be taken not to damage this coating by cleaning. A fine brush can be used for removing loose particles/dust. If this is not sufficient the window should by cleaned using a soft paper tissue or cloth and some window cleaning liquid.
Battery
The LTL2000S(Q) Retroreflectometer is powered by a sealed 12V/3.5Ah lead acid battery, which under normal use requires no maintenance. However it is recommended to keep the battery fully charged. A fully charged battery is more capable of withstanding low tempera- ture and ageing.
Battery charger is provided as a standard accessory for charging the battery from mains. The output cable of the charger is equipped with a socket matching the connector in the instru- ment. Connect charger to mains and instrument. The red indicator will be switched on as long as the charging is in progress. Thereafter it switches periodically on and off. Normally the charging will take about 8 hours. Typically the battery achieves 90% of the capacity in 5 hours. No harm will result from leaving the charger connected for time in excess of the above indicated duration of the charging process. However, the battery must be disconnected from the charger when disconnecting the mains.
The battery is located in a compartment at the front of the tower. To replace the battery re- move the screws holding the right side cover plate, seen from behind. Remove the screws from the right hand side of the red front- and back cover plate. Remove the side cover plate. Remove the 2 nuts holding the clamp plate. Lift out the battery of its container. The battery can now be removed and replaced. Refit in reverse order.
Fuses
Fuses, two pieces, are placed at the rear of the instrument. The charging fuse protects the bat- tery against short circuit and other errors in the charging connector, charger or charging sys- tem.
The battery fuse protects battery and electronics against short circuit and other errors in the electronic system.
Always replace a blown fuse with one of equal rating. To change a fuse carefully unscrew the plastic cap fuse holder by using e.g. a coin. Pull out the fuse from the cap and insert the new one and reassemble
Lamp
The halogen lamps requires no maintenance. At life end they must be replaced. It is recommended that replacing is done by trained personal.
Calibration unit
The road marking is simulated by a piece of white ceramics mounted on a aluminium block with a small grip. Ceramics has very stable optical properties and cleaning is easy because of the smooth surface.
Rl calibration unit
Ceramics
Qd calibration unit
Figure 9. Calibration units
To make sure that calibration of the retroreflectometer is correct it is important that the ceram- ics on the calibration unit is clean and undamaged. All ways keep the calibration unit well protected.
If the ceramics is stained, scratched or broken the calibration unit has to be replaced.
In case of dust on the ceramics surface, clean gently with a damp soft cloth if necessary use a
mild household detergent.
To ensure reliable measurements, it is recommended that the calibration unit is periodically recalibrated to a traceable standard. DELTA Light & Optics offers calibration traceable to PTB
Light trap
Zero signals are simulated by a light trap made of two glossy and black plastic sheets moun- ted in an acute angle. If clean this will provide very efficient light absorbing device.
Rl calibration unit
Light trap
Figure 10. Light trap
It is necessary to disassemble the light trap to clean it efficiently. This is easily done by lifting and pulling it. Cleaning can be done by using a fine brush, clean pressurised air or a soft paper tissue/cloth and some window cleaning liquid.
Pull and lift the upper
Figure 11. Cleaning
Printer
The printer is a high speed high quality mini thermal printer. It has only a few moving parts and does not require any special or periodic maintenance.
Paper specification:
???thermal paper
???width: 57.5 mm
???diameter: 31 mm (max.)
Replacing the paper is easily done by opening the paper container with the little handle in the cover, just place the new paper role with a short paper tail hanging out at the top and close the cover with a firm push.
Figure 12. How to replacing the printer paper.
APPENDIX A
COMMUNICATION FACILITIES
The LTL2000S(Q) is equipped with a communication facility that enables the use of a simple data terminal or an ordinary PC type computer for control of LTL2000S(Q) functions and for log data acquisition.
The computer or terminal connects to the Instrument using a communication cable fitted with a 9 pin male
The electrical connections meet the
Connections in the 9 pin
Connection example #1. PC with
Connection example #2. PC with 9 pin
As it can be seen, the interconnections have been held to an absolute minimum, and in some rare situations there will have to be established additional connections on the PC side. Please refer to your PC manual for further information.
Data protocol
The communication between the LTL2000S(Q) and the computer equipment takes place us- ing the following settings:
Command format
All LTL2000S(Q) commands are built using the following template.
Command End (Carriage Return, mandatory)
Example #1:
The user wants to see how the Automatic Off timer is set and then change the value to 120 seconds.
The command and the response sequence look like this.
Ot
Automatic Off Timer = 300 sec.
Ot 120
Automatic Off Timer = 120 sec
If for some reason the communication fails or the command is undefined the LTL2000S(Q) responds with a question mark. <?>
If the parameter lies outside the defined range for that parameter, the LTL2000S(Q) returns the present setting without any change.
Example #2:
The user wants to read the data in the data log
The command and the response sequence can look like this.
Command set
The instrument is equipped with a serial communication port primarily for log data acquisition, calibration and test, however all normal instrument functions can be controlled from this interface.
The following commands have been defined
Command set
Command set
E.g. Status code 18 is composed of Low Battery Warning (16) + Stray Light Warning (2)
APPENDIX C
Print outs
Result Printout
Examples of result printouts showing the measured values, the Measurement Id and the number of measurements with this id, the number of measurements used to calculate the mean value, the date and time the measurement was taken, the number of data in the data log, the measurement status and the instrument serial number.
Note that one or more of the shown data can be left out depending on the selected operation mode.
If the status is other than 0 then there was a special condition detected during the measurement and this will also be printed.
Rl Calibration Printout
The printout after a Rl Calibration measurement showing the selected Rl Normal value. The date and time for the calibration and the status for the measurement.
Qd Calibration Printout
The printout after a Qd Calibration measurement showing the selected Qd Normal value, the date and time for the calibration and the status for the measurement.
Note: The Calibration printout can only follow directly after a calibration with the 
key.
Log Printout
Example of log printout from LTL2000SQ
The printout shows the instrument s/n, number of entries, number of free log entries, a data header and then all the data listed with the newest first, if one of the measurement modes has been disabled the result entry will show ???off??? for that measurement.
The printout is done from the Menu system.
Status Printout
Example of status printout. The printout is done from the Menu system.
Date and time for printout
Zero adjust data
Rl calibration data
Rl measurement data
Qd Calibration data
Qd measurement data
Voltage measurements
Log status
Error info
Instrument info
Firmware info
APPENDIX C
SPECIFICATION
General Characteristics Rl
General Characteristics Qd
