Ahlborn ALMEMO 2690-8 User manual

____________________________
Operating Instructions
Data Logger
ALMEMO® 2690-8
V1.0
29.06.04
www.ahlborn.com

1. Operating Controls
1. OPERA ING CON ROLS
(1) Meas. inputs M0 to M4
M0 ... M4 for all ALMEMO-Sensors
M10...M34 1 additional channels
(2) Output sockets A1, A2
A1 Interface V24 (ZA 1909-DK5)
Fiber optics V24 (ZA 1909-DKL)
Ethernet (ZA 1945-DK)
Centronics (ZA 1936-DK)
RS 422 (ZA 5099-NVL/NVB)
Analog output 1 (ZA 1601-RK)
A2 Network cable (ZA1999-NK5/NKL)
Trigger input (ZA 1000-ET/EK)
Relay outputs (ZA 1000-EGK)
Analog output 2 (ZA 1601-RK)
(3) Connector socket DC 12V
Mains adapter(ZA 2690-NA, 12V, 0.2A)
Charging adapter (ZA 2690-LA, 12V)
DC-Cable isolat. (ZB 2690-UK, 10-30V)
(4) Sleep-LED
(5) LCD display
Status line:
CCont. measuring point scan
© , ll Measurement Start, Stop
REC Memory record
COM Output of meas. values
l©, ©l Meas. start, end programmed
R01 Alarm relay status
* , * Light on, pause
Battery operation/charge status
13 lines for functions
Function of keys F1, F2, F3, F4
(6) Control keys
ON , <POFF> Switch device on, off
 ,  ,  Function selection
F1 ... F4 Function keys ( oft key )
PROG Programming
 ,  ,  Data input
<ESC> Function abort
 Last measuring menu
(7) Rubber shock absorber
2 ALMEMO 2690-8
4
5
6
7
123
8
Back of unit:
(8) Battery box
3 Mignon Alkaline Batteries
or 3 Mignon NiCd/NiMH Accumulator
(9) Stand for stand and hang up
(for opening out from 90° to 180°
please press the stand together!)

Table of Contents
2. ABLE OF CON EN S
1. OPERA ING CON ROLS...........................................................................2
2. ABLE OF CON EN S
3. GENERAL.....................................................................................................6
3.1 Guarantee..............................................................................................6
3.2 Extent of the Delivery ..........................................................................7
3.3 Handling Batteries or Accumulators.................................................. 7
3.4 Special Operating Instructions............................................................7
4. IN RODUC ION..........................................................................................8
4.1 Function Range of the ALMEMO 2690-8............................................ 8
4.1.1 Sensor Programming.....................................................................8
4.1.2 Measurement...............................................................................10
4.1.3 Process flow control.................................................................... 11
5. INI IAL OPERA ION.................................................................................13
6. POWER SUPPLY.......................................................................................14
6.1 Battery operation and Supply Voltage Control................................14
6.2 Accumulator operation.......................................................................14
6.3 Mains Operation..................................................................................14
6.4 External DC Voltage Supply.............................................................. 15
6.5 Sensor Supply.....................................................................................15
6.6 Switch On/Off, Reinitialisation..........................................................15
6.7 Data buffering.....................................................................................15
7. CONNEC ION OF HE RANSDUCERS.................................................16
7.1 ransducers........................................................................................16
7.2 Measuring inputs and Additional Channels.....................................16
7.3 Isolation...............................................................................................17
8. DISPLAY AND KEYPAD............................................................................18
8.1 Display and Menu Selection..............................................................18
8.2 Function Keys ....................................................................................19
8.3 Control Symbols.................................................................................19
8.4 Function Selection..............................................................................20
8.5 Data Entry............................................................................................20
9. MEASURING USING MEASURING-MENUS............................................21
9.1 Measuring with one Measuring Point...............................................22
9.1.1 Selecting the Measuring Point.....................................................22
9.1.2 Peak Value Memory with Time and Date.................................... 22
9.2 Correction of the Meas. Value and Compensation ........................ 23
9.2.1 Setting the Meas. Value to Zero..................................................23
9.2.2 Zero Point Adjustment ................................................................24
9.2.3 Sensor Adjustment in the case of chemical sensors...................24
9.2.4 Two-point Adjustment with Setpoint Entry...................................2
ALMEMO® 2690-8 3

2. Table of Contents
9.2. Temperature Compensation .......................................................26
9.2.6 Atmospheric Pressure Compensation.........................................26
9.2.7 Cold Junction Compensation.......................................................27
9.3 Measuring point scans and Output.................................................. 28
9.3.1 Single Output / Storage of all Measuring Points..........................28
9.3.2 Cyclic Output / Storage of all Measuring Points.......................... 28
9.3.3 Memory space, Memory Output, Clearing the Memory...............29
9.3.4 Output of Menu Functions...........................................................29
9.3. Displaying Measured Values as a Line Diagram ........................30
9.4 Averaging............................................................................................31
9.4.1 Damping of Meas. values by a Sliding averag. window.............. 32
9.4.2 Averaging Mode...........................................................................32
9.4.3 Averaging over Manual Single Measurements............................32
9.4.4 Net Measurement........................................................................33
9.4. Averaging over the Measuring Time............................................34
9.4.6 Measurement Time......................................................................34
9.4.7 Averaging over the Cycle.............................................................3
9.4.8 Averaging over several Measuring Points...................................36
9.4.9 Volume Flow Measurement.........................................................37
9.5 Display of Several Measuring Points ...............................................38
9. .1 Menu Multi Channel Display and Bar chart................................. 38
9. .2 Differential Measurement............................................................38
9. .3 Menu List of Measuring Points....................................................39
9.6 Assistant-Menus for Special Meas. Operations.............................. 40
9.6.1 Thermal Coefficient.....................................................................40
9.6.2 Wet Bulb Globe Temperature......................................................40
9.7 User Menus.........................................................................................41
9.7.1 Functions.....................................................................................41
9.7.2 Configuration of the menus ........................................................ 42
9.7.3 Function Printouts........................................................................43
9.7.4 Programming via the Serial Interface:.........................................44
10. PROGRAMMING WI H PROGRAMMING-MENUS..................................45
10.1 imes and Cycles.............................................................................45
10.1.1 Time and Date ..........................................................................4
10.1.2 Cycle with Storage Activation and Output Format.....................4
10.1.3 Conversion Rate, Continuous Measuring Point Scan............... 46
10.1.4 Time and Date of Start, Time and Date of End ........................ 47
10.2 Data Memory.....................................................................................48
10.2.1 Data Acquisition.........................................................................48
10.2.2 Numbering of measurements....................................................49
10.2.3 Starting and Stopping of measurements...................................49
10.2.4 Sleepmodus...............................................................................49
10.2. Memory Output.......................................................................... 0
10.3 Sensor Programming.......................................................................52
4 ALMEMO 2690-8

Table of Contents
10.3.1 Selecting the Input Channel....................................................... 2
10.3.2 Measuring Point Designation..................................................... 3
10.3.3 Averaging Mode......................................................................... 3
10.3.4 Locking the Programming of the Sensor................................... 3
10.3. Limit Values............................................................................... 4
10.3.6 Scaling, Decimal Point Setting.................................................. 4
10.3.7 Correction Values......................................................................
10.3.8 Changing the Dimension...........................................................
10.3.9 Selecting the Measuring Range................................................
10.3.10 Function Channels .................................................................. 8
10.4 Special Functions.............................................................................59
10.4.1 Print Cycle Factor...................................................................... 9
10.4.2 Minimum Sensor Supply Voltage.............................................. 9
10.4.3 Limit Value Responses..............................................................60
10.4.4 Analog Output Start and End.....................................................61
10.4. Output Function.........................................................................61
10.4.6 Reference Channel 1.................................................................62
10.4.7 Reference Channel 2 or Multiplexer..........................................62
10.4.8 Element Flags............................................................................62
10.5 Device Configuration........................................................................63
10. .1 Device Designation....................................................................63
10. .2 Device Address and Networking............................................... 63
10. .3 Baud Rate, Data Format............................................................64
10. .4 Language...................................................................................64
10. . Lighting and Contrast.................................................................64
10. .6 Atmospheric Pressure...............................................................64
10. .7 Hysteresis..................................................................................6
10. .8 Operating Parameters...............................................................6
10.6 Output Modules................................................................................65
10.6.1 Data cable..................................................................................66
10.6.2 Relais Trigger Cable..................................................................66
10.6.3 Analog Output............................................................................67
10.7 Menu Power Supply..........................................................................68
11. ROUBLESHOO ING...............................................................................70
12. ELEC ROMAGNE IC COMPA IBILI Y..................................................71
13. APPENDIX..................................................................................................72
13.1 echnical Data ................................................................................. 72
13.2 Product overview .............................................................................72
13.3 Keyword index..................................................................................73
ALMEMO® 2690-8

3. General
3. GENERAL
Congratulations for buying this innovative ALMEMO® data logger. By means of
the patented ALMEMO® connectors the device configures itself and with the
help of menus and help windows the operation should not be too difficult. Ho-
wever, the device allows the connection of a great variety of sensors and peri-
pherals with many special functions. For getting to know the function range of
the sensors and the diverse possibilities of the device, you really should read
these operating instructions and the corresponding chapters of the ALMEMO
®
manual. This is the only way to avoid operating and measuring errors as well
as damages of the device. For a quick answer to all questions, a detailed key-
word index is provided at the end of the instructions and of the manual.
3.1 Guarantee
Every device has to pass through several quality tests before leaving the
works. For a perfect function, a guarantee of two years from the delivery date
is granted. Before sending back the device, please pay attention to the indica-
tions in chapter 11. Troubleshooting. Should there actually be a defect, please
use the original packing material for depatch if possible and enclose an ex-
pressive description of the trouble in connection with the corresponding circum-
stances.
In the following cases a guarantee benefit is excluded:
After forbidden operations and changes in the device by the client
Operating in surrounding conditions that are not valid for this product
Using unsuitable power supply and peripherals
Using the device in a way it is not determined for
Damages through electrostatic discharge or flash of lightning
Not paying attention to the operating instructions
Changes in the product features in favour of technical progress or due to new
components are reserved to the producer.
6 ALMEMO 2690-8

Extent of the Delivery
3.2 Extent of the Delivery
While unwrapping the delivery, pay attention to damages of the device and to
its completeness:
Measuring device ALMEMO® 2690-8 with 3 alkaline-mignon-batteries,
Rubber shock absorber with a stand,
these operating instructions,
ALMEMO® Manual,
CD with Software AMR-Control and useful accessories
In case of a transportation damage, the packing material is to be kept and the
supplier is to be informed immediately.
3.3 Handling Batteries or Accumulators
When putting in the batteries/accumulators the right pole is to be
considered.
Remove the batteries from the device when they are empty or
when the device is not used for a long time in order to avoid
damages through running out cells. Accumulators should corre-
spondingly be charged in time.
Batteries are not to be charged, danger of explosion!
Pay attention to batteries/accumulators not being short-circuited
or thrown into the fire.
Batteries/accumulators are special refuse and must not be
thrown in the dustbin!
3.4 Special Operating Instructions
When the device is brought from cold surroundings into the work room, the-
re can appear some kind of dew on the electronic. At thermocouple measu-
rements and high changes in temperature, greater measuring errors are
additionally possible. Therefore, please wait until the device is adapted to
the ambient temperature before operating with it.
When connecting mains adapters the mains voltage is to be considered
Pay attention to the maximum capacity of the power supply of the sensors
Sensors with supply are not electrically isolated from each other.
Do not lay the sensor cables near power lines.
Mind the diversion of statical electricity before touching the sensor cables.
Opening out the stand (9) at the back of the rubber shock absorber (7) you
can bring the device in a sloping position for a better legibility. When you
press the stand together, it can also be folded up over the stop in order to
hang up the device on corresponding gadgets.
ALMEMO® 2690-8 7

4. Introduction
4. IN RODUC ION
The data logger ALMEMO® 2690-8 is a new instrument from the unique pro-
duct range of measuring devices that are all equipped with the ALMEMO®
connector system, which has been patented by Ahlborn GmbH. The intelligent
ALMEMO® connector provides important advantages with regard to the
connection of sensors and peripherals as all parameters are stored in an EE-
PROM within the connector. As a result, the programming that usually has to
be performed for the connection is not required. All sensors and output modu-
les can be connected to all ALMEMO® measuring devices in the same way.
The operation and programming is identical with all units. Therefore, all of the
ALMEMO® measuring system items listed below are described, in detail, in a
separate ALMEMO® manual that is supplied with every device:
Detailed description of the ALMEMO® system (manual section 1)
Overview of the device functions and measuring ranges (manual section 2)
All sensors with basic principles, operation, technical data (man. section 3)
The options for connecting existing sensors (manual section 4)
All analog and digital output modules (manual section .1)
The interface module RS232, fiber optics, Centronics (manual section .2)
The entire ALMEMO® networking system (manual section .3)
All functions and their control via the interface (manual section 6)
A complete interface command list with all print outputs (manual section 7)
These operating instructions only cover features and controls that are specific
for a certain device. As a result, many sections will often provide a note
referring to the more detailed description within the manual (man. sect. x.x.x).
4.1 Function Range of the ALMEMO 2690-8
The ALMEMO® 2690-8 data logger has electrically isolated measuring inputs
for all ALMEMO® sensors. Over 20 channels in the sensor connectors and 4
device internal function channels with more than 70 measuring ranges are pro-
vided with unlimited measuring possibilities. The device can be operated by
means of the LCD graphic display and a softkey keypad with cursor block.
User menus can be configured to adapt the display for any application. The
data logger function is carried out by a real time clock and a 12kB EEPROM
memory for approximately 100000 measured values. Two output sockets allow
for connecting any ALMEMO® output modules, for example, the analogue out-
put, digital interface, trigger input or alarm contacts. Several devices can be
networked by simply connecting them with network cables.
4.1.1 Sensor Programming
The measuring channels are automatically programmed by the ALMEMO®
8 ALMEMO 2690-8

Function Range of the ALMEMO 2690-8
connectors. However, the user can easily complete or modify the programming
via keyboard or via interface.
Measuring Ranges
There are corresponding measuring ranges for sensors with a non-linear
characteristic such as 10 thermocouple types, Ntc and Pt100 sensors, infrared
sensors, and flow sensors (rotating vanes, thermoanemometers, pitot tubes).
Humidity sensors are available with function channels that also calculate humi-
dity data such as dew point, mixture ratio, vapour pressure and enthalpy. Even
complex chemical sensors can be used. The acquisition of measured data
from other sensors is easily possible by using the voltage, current and resistan-
ce ranges with individual scaling in the connector. Existing sensors can be
used without problems. Only the corresponding ALMEMO® connector has to
be connected using its terminals. Furthermore, there are adapter connectors
with an own microcontroller for digital signals and for measuring frequencies
and pulses. This way, nearly all sensors can be connected to any ALMEMO
®
measuring instrument and are interchangeable without requiring any settings.
Function Channels
Maximum, minimum, average values and differences of certain measuring
junctions can be programmed as function channels, also in device internal
channels, and can be processed and printed like normal measuring junctions.
Furthermore, function channels for special measuring tasks are provided to de-
termine the temperature coefficient Q/DT and wet bulb globe temperature.
Dimension
The 2 digit dimension can be altered for each measuring channel so that the
display and the printout will always indicate the correct dimension, for example
when a transmitter is connected. The conversion from °C to °F is automatically
performed according to the dimension.
Name of Measured Values
For identification of the sensors a 10-digit alphanumeric name is provided. It is
entered via the keypad or the interface and appears on the display, the printout
or the computer display.
Correction of Measured Values
For correcting measured values a zero point and slope correction can be app-
lied to the measured value of each measuring channel. This also allows for
sensors to be interchanged that usually, at first, require an adjustment (expan-
sion, force, pH). The zero point and the slope correction are virtually performed
by the push of a button.
Scaling
The base value and the factor allow for a further scaling of the corrected mea-
ALMEMO® 2690-8 9

4. Introduction
sured value of each measuring channel for zero point and slope. The decimal
point position can be set by the exponent. By setting to zero and entering the
nominal value the scaling values can be automatically calculated.
Limit Values and Alarm
Two limit values (1 max and 1 min) can be set for each meas. channel. If a
limit value is exceeded alarm contacts, that can be individually allocated to limit
values, are provided by means of relay output modules. As a standard, the
hysteresis is set to 10 digits; however, it can also be adjusted between 0 and
99 digits. Furthermore, limit value exceeding can also be used to start or stop a
data logging.
Sensor Locking
All sensor data stored in the EEPROM of the connector can be protected
against undesired access by means of a graded locking function.
4.1.2 Measurement
A total of up to 20 meas. channels are available for transducers, i.e. it is also
possible to evaluate double sensors, individually scaled sensors, or sensors
with function channels. The meas. channels can be successively selected for-
wards or backwards via keypad. Normally, the selected meas. point is favou-
red, but all active meas. channels are also scanned in the background
(halfcontinously) with the conversion rate and output to the display or, if availa-
ble, to the analog output. To increase the response speed at many measuring
points, the conversion rate can be increased and set to continuous scan.
Measured Values
The measured values of 1 to 20 measuring points can be indicated on the dis-
play in different menus (that can also be configured) in three font sizes, as bar
graph or as line chart. They are automatically acquired with auto zero and self
calibration and can also be arbitrarily corrected and scaled as required. A sen-
sor breakage condition is, with most sensors, automatically detected.
Analog Output and Scaling
By means of analog start and analog end any measuring point can be scaled
so that the resulting measuring range covers the full range of the bar graph or
line chart or of an analog output (2V, 10V or 20mA). The measured value of
any measuring point as well as a programmed value can be output to the ana-
log output
Measuring Functions
Special measuring functions are required for some sensors to achieve an
optimal data acquisition. The cold junction compensation is available for
thermocouples, a temperature compensation for dynamic pressure and pH and
conductivity probes, and an atmospheric air pressure compensation for humidi-
ty sensors, dynamic pressure sensors and O2 sensors. With infrared sensors
the parameters zero point and slope correction are used for background tem-
perature and emissivity factor.
10 ALMEMO 2690-8

Function Range of the ALMEMO 2690-8
Max and Min Value
Each measurement involves an acquisition and storage of the Max value and
the Min value including the time and date. The values can be displayed, printed
or cleared.
Average Value
A manual averaging over a particular period, cycle or over single measure-
ments is available for every channel.
4.1.3 Process flow control
A continuous measuring point scan with a time-based process flow control for
the output of measuring valures is required to register the measuring data of all
connected sensors. For this purpose, an output cycle is available and, if fast
processing is required, the conversation rate is available. The measurement
can be started and stopped by using the keyboard, the interface, an external
trigger signal, the real time clock or an exceeding of limit values.
ime and Date
The real time clock with data function or the pure measuring time are used for
an accurate recording of any measurement. Start and end time/date can be
programmed in order to start or stop a measurement.
Cycle
The Cycle is programmable between 1 s and 9 h, 9 min and 9 s and provi-
des a cyclic output of measured values to the interfaces or memories and also
provides a cyclic averaging.
Print Cycle Factor
If necessary, the print cycle factor allows for limiting the data output of particu-
lar channels so that an excessice data flow can be limited, especially during
data storage.
Average Value over Measuring Point Scans
The measured values resulting from scanning measuring junctions can be ave-
raged as desired either over the total measuring time or over the cycle time.
Function channels are available for a cyclic output and storage of these ave-
rage values.
Conversion Rate
With the ALMEMO® 2690-8 all measuring points can be continuously scanned
with the conversion rate (2. ;10 or 0 M/s). To realize a high recording speed it
is possible to store all measured values in the memory and/or to perform an
output via the interface.
Data Memory
During the cycle, all measured values can be manually or automatically stored
in an EEPROM. The memory capacity is, as standard, 12 Kilobyte, which al-
lows up to 100.000 measured values. The memory organisation can be confi-
gured as linear or ring memory.The output can be carried out via the display or
ALMEMO® 2690-8 11

4. Introduction
the interface. It is possible to specify a selection according to a time interval or
number.
Numbering of Measurements
By entering a number, single scans or entire series of measurements can be
identified and selectively read out from the memory.
Control Outputs
Via keyboard and interface allows to individually trigger up to 4 output relays
and one analog output.
Operation
All measuring and function values can be displayed in different menus on the
dot matrix LCD display. 3 user menus can be individually configured from near-
ly 0 functions for your specific applications. Using texts, lines and blank lines
allows to format the printout in an application-specific style. Nine keys (four of
them are soft keys) can be used to operate the device. This also allows you to
fully program the sensors, the device and the process control.
Output
All data logs, menu functions and stored measured values and programmed
parameters can be provided as output to any peripheral equipment. Various in-
terface cables can be used to provide a RS232, RS422, Centronics or Ethernet
interface. The output of measuring data can be selected in list format, columns
or spreadsheet format. Files in spreadsheet format can be processed by each
spreadsheet software. The print header can be programmed specifically to the
company or application.
Networking
All ALMEMO® devices can be addressed and can be easily networked by sim-
ply linking them using network cables, or RS422 network distributors for longer
distances.
Software
The AMR-Control software, which allows for the entire programming of the
sensors, the configuration of the measuring instrument, of the user menus and
the read-out of the data memory is supplied with each ALMEMO®manual. The
integrated terminal also allows for online measurements. The WINDOWS®
software WIN-Control is available for data acquisition of networked devices,
graphical presentation and complex data processing.
12 ALMEMO 2690-8

Initial Operation
5. INI IAL OPERA ION
Sensor connection Connect transducers to the sockets M0 to M4 (1), . 7.
Power supply with batterie /accumulator or main adapter on DC (3) . 6.1, 6.3
Switch-on Press key ON / PROG (6), . 6.6
Automatical display of the last measuring menu, . 9. keys:
Menu selection MEAS.-Menus: call up with key: < ESC > or F4
e.g. select menu StandardDisplay , . 8.1  /  ... ( F )
Call up the menu with key: 
Select meas. point ( . 9.1.1) with keys:  /  ... ( M )
Select function Max/MinVal ( . 8.4) with: PROG ,  ...
Clear max/min values, . 9.1.2 < CLR > or F1
Output of measuring data or memory via interface:
- Connect peripheral device, via data cable, to socket A1 (2), s. man. .2
- Set 9600bd, 8 data bits, 1 stop bit, no parity at peripheral device
Single output/storage, . 9.3.1 < MANU > or F2
Cyclic measurement: Select Cy le-Timer : PROG ,  ...
Enter cycle (hh:mm:ss) . 8.5 Cy le-Timer: 00:05:00Sn
Output format list ´ ´, columns ´n´, table ´t´ < FORM> or F3 ...
Stop programming < ESC> or F4
Start/stop the cyclic measurement, . 9.3.2 <START> , <STOP> or F1
Output of memory data to printer or computer:
Select the function Memory Free with: PROG ,  ...
Memory data output, . 10.2.5 < PRINT> or F3
Clear memory, . 10.2.5 < CMEM >
ALMEMO® 2690-8 13
F1 F2 | F3 F4

 ON PROG 

F1 F2 | F3 F4

 ON PROG 

* ALMEMO 2690-8 *
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
MEASURING-Menus:
Standard display ©
U1 Meas. value orre tion
U2 Averaging
U3 Volume flow
Data logger
Multi hannel display
*List of measuring points
Bar harts
Line diagram
_____________________
Menu1 PROGRAMMING-Menus
Menu2 ASSISTANT-Menus
POFF *ON F MENU1 MENU2
C © REC COM l© ©l R01 * ´´´´´´µµµµ¶
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
01: Velo ity m/s
æ » H º
28.67
Maximum value: 31.34 mls
Minimum value: 25.37 mls
Cy le-timer: 00:02:30 Un
Memory free: 512.0 kB
START MANU M PRINT ESC

6. Power supply
6. POWER SUPPLY
The following options are available for the power supply of the instrument:
3 alkaline-mignon batteries (type AA) in the extent of the delivery
Mains adapter 12V, 0.2A with ALMEMO® connector ZB 2690-NA
3 NiMH-accumulators (type AA) with charging adapter 12V,1A ZB 2690-AS
Electr. isol. power supply cable (10..30V DC, 0.2 A) ZB 2690-UK
Our product line includes corresponding accessories.
6.1 Battery operation and Supply Voltage Control
3 mignon batteries are used as the standard power supply of the device. At a
current consumption of approx. 30 mA, they last for an operating time of about
100 hours. If the illumination is constantly switched on, this operating period is
reduced to approx. 20 to 0 hours (depending on the lightness). To extend the
operating time for long term recording it is possible to operate the device in
sleep mode (s. 10.2.4). The current operating voltage can be called up in menu
Power supply (s. 10.7) in order to assess the remaining operating time.
When a remaining battery capacity of approx. 10% is reached, the symbol ´´µµµµµµµµµ¶
will be indicated in the status line of the display. If the battery is completely
discharged, the device will switch off. However, measuring data and time will
be maintained (s. 6.7). To change the batteries, the sensors must be taken off,
the rubber protection (7) be removed and the battery cover (8) at the back of
the device has to be unscrewed and stripped off in the direction of the arrow.
6.2 Accumulator operation
The batteries can also be replaced by 3 NiMH accumulators. In the accessory,
there is a corresponding accumulator set with charging adapter (ZA 2690-AS).
As the capacity of the accumulator is only about the half of the alkaline-
manganese batteries, the operating times get half as long as well. The char-
ging adapter is to be connected between mains adapter and measuring device.
It discerns the maximum current of the mains adapter and correspondingly
adjusts the charging time. Maximum current, charging current and charging
time can be controlled in the menu Power supply (s. 10.7). If the accumula-
tors are completely charged, the charging adapter switches to trickle charge.
Therefore, it can stay continuously connected to the measuring device without
overcharging the accumulators.
6.3 Mains Operation
For external supply of the device the mains adapter ZA 2690-NA (12V/0.2A)
must be connected to the socket DC (3). Pay attention to the mains voltage!
Operating with accumulator, the stronger mains adapter ZA 2690-NA2
(12V/0.8A) allows an especially fast charging of the accumulators in 1 hour.
14 ALMEMO 2690-8

External DC Voltage Supply
6.4 External DC Voltage Supply
It is also possible to connect another DC voltage, 6..12V (min. 200mA), to the
socket DC (3).The connection is performed by using an ALMEMO® connector.
However, the electrically isolated supply cable ZB 2690-UK must be used if an
electrical isolation between power supply and transducers is required or if a
larger input voltage range 10...30V is required. It allows to operate the measu-
ring instrument with 12V or 24V DC on-board supply systems.
6.5 Sensor Supply
A configurative sensor supply voltage is provided at the clips – and + in the AL-
MEMO® connector (self-repairing fuse 00 mA). Instead of the 9V (1 0mA) as
a standard, it is possible to program 6V (200mA) for power saving or 12V (100-
mA) if necessary, in the menu Power Supply (s. 10.7), according to the de-
mand of the sensors. Other voltages (12V, 1 V, 24V or references for
potentiometer and strain ganges) are also available with special connectors (s.
man. 4.2. /6).
6.6 Switch On/Off, Reinitialisation
To switch on the device press the key ON PROGr (6) in the middle of the cursor
block. There always appears the last called up meas. menu first in the display.
To switch off the device leave a working menu with <ESC>r and press the soft-
key <P-OFF>r in the menu selection. After switch-off the real time clock conti-
nues its operation and all stored data remains available (s. 6.7).
If the device shows an irregular behaviour due to interference influences (e.g.
electrostatic charging or battery failure), the device can be reinitialised. The
reset can be achieved if the key F1 r is pressed during switch-on. If the com-
plete device programming with times, terms of device, user menus etc. is to be
set to the delivery defaults, the key F4 r must be pressed during switch-on.
Only the sensor programming within the ALMEMO® connectors will not be atta-
ched by this reset.
6.7 Data buffering
The sensor programming is stored in the EEPROM of the sensor connector,
the calibration and the programmed parameter of the device is fail-safe stored
in the EEPROM of the device. Time and date are buffered by a lithium battery
so that storage of the data is also guaranteed without batteries and when the
device is switched off.
ALMEMO® 2690-8 1

7. Connection of the Transducers
7. CONNEC ION OF HE RANSDUCERS
Any ALMEMO® sensors can be connected to the ALMEMO® input sockets M0
to M4 of the measuring instrument (1). For connecting existing sensors it is
only necessary to connect a corresponding ALMEMO® connector.
7.1 ransducers
A detailed description of the comprehensive ALMEMO® sensor range (see ma-
nual section 3) and the connection of existing sensors (see manual section 4)
to the ALMEMO® instruments are provided in the ALMEMO® manual. All stan-
dard sensors with ALMEMO® connector usually have the measuring range and
dimension already programmed and can be immediately connected to any in-
put socket. A mechanical coding ensures that sensor and output modules can
only be connected to the correct sockets. Furthermore, each ALMEMO®
connector has two locking levers that snap in when the insertion into the socket
is established and that prevent a disconnection caused by pulling the cable.
Both levers must be pressed on the sides for disconnecting the connector.
Especially for the device ALMEMO® 2690-8, new sensors with ready-made AL-
MEMO® connectors are available. They offer a splash-proof enclosure for the
sockets due to their double sealing lips. For unused sockets there are dummy
connectors.
7.2 Measuring inputs and Additional Channels
The measuring instrument ALMEMO 2690-8 has input sockets (1) that the
measuring channels M0 to M4 are initially allocated to. However, ALMEMO
®
sensors can, if required, provide up to 4 channels so that 20 channels are
available with input sockets. The additional channels can be especially used
with humidity sensors with 4 measuring variables (temperature/humidity/dew
point/mixture ratio) or used for function channels. If required, the sensor can
also be programmed with several ranges or scaling or, depending on the pin
assignment, 2 or 3 sensors can be combined in one connector (e.g. rH/Ntc,
mV/V, mA/V etc.). The additional measuring channels of a connector are incre-
ased in steps of 10 (e.g. the first sensor has the channels M0, M10, M20, M30,
the second sensor has the channels M1, M11, M21, M31 etc.).
Device-internal channels:
An innovation on this device is its four extra additional channels. The first of
these M is programmed by default as differential channel M1 – M0. This only
happens, however, if there are two sensors with the same units and same de-
cimal point position connected at measuring points M0 and M1. However, all
four channels can be programmed with any other function channels (e.g. U-
Bat, CJ, average, volume flow, etc.); (s. 10.3.10, man. 6.3.4). Mb1 = M1 and
Mb2 = M0 are always used as reference channels by default.
16 ALMEMO 2690-8

Measuring inputs and Additional Channels
Advantage of the device-internal channels: If several sensors are being used
for the same application, they do not have to be reprogrammed and can be
freely exchanged without losing their function channels. If, however, the whole
application operates with just one sensor, then programming in the sensor
itself makes more sense.
On the measuring instrument this gives the following channel assignment:
7.3 Isolation
When building up a working measuring arrangement, it is very important that
there cannot flow any compensation currents between sensors, power supply
and peripherals. This is the case when all measuring points are on the same
potential or when unequal potentials are electrically isolated.
The analog inputs are electrically isolated by photovoltaic relais and between
them a potential difference of at most 0 V DC or 60V AC is permitted. Howe-
ver, combined sensors within one connector and sensors with power supply
are elelctrically connected; therefore they must be operated isolatedly. The vol-
tage at the measuring inputs (between B,C,D and A or -) must not exceed 12V!
The power supply is isolated by the transformer of the mains adapter or by the
DC/DC-converter in the adapter cable ZA2690-UK. Data and trigger cables are
equipped with optocouplers. At electrically not isolated cables of the analog
output, the registration device or the sensors have to be potential free.
ALMEMO® 2690-8 17
M0 M1 M2 M3 M4
00
10
20
30
03
13
23
33
04
14
24
34
01
11
21
31
02
12
22
32
1. Channel
A2 A1 DC
0
1
2
3
Device-internal channels
Difference M01-M00
Sensor channels
2. Channel
3. Channel
4. Channel
M2
M1
M0
Data cable
AC
DC
DC
DC
ADC uC
U-
U+
Sensors
Power supply
10..30V=

8. Display and Keypad
8. DISPLAY AND KEYPAD
8.1 Display and Menu Selection
The display ( ) of the measuring instrument ALMEMO 2690-8 consists of a dot
matrix LCD display with 128x128 dots, or 16 lines with 8 dots. For the acquisiti-
on of measuring data with the required functions and for the programming of
the process control, the sensors and the device parameters, 3 categories of
menus are available: Measuring-Menus (s. 9), Programming-Menus (s. 10)
and Assistant-Menus, which can be called up over corresponding selecting
menus. Of the 9 measuring menus, there are 3 ´user´ menus U1, U2, U3,
which are freely definable by the user (s. 9.7).
If necessary, call up the menu selection using the key: <ESC>
If necessary, select the desired menu selection with key: <MENU1> o. <MENU2>
Switch on the Display Lighting in 3 levels (s. 10. . ) <  ON >
Switch off the device with key: <P-OFF>
Select the menus using the keys:  or  ...
Call up the selected menu with key:  or PROG
Back to the last meas. menu using the key once: 
Back to the last programming menu using the key again: 
Back to the menu selection with key: <ESC>
The device designation in the header line can be as easily pro-
grammed(s. 10. .1) as the menu titles of the user menus (s. 9.7).
18 ALMEMO 2690-8

* ALMEMO 2690-8 *
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
MEASURING-Menus:
Standard display ©
U1 Meas. value orre tion
U2 Averaging
U3 Volume flow
Data logger
Multi hannel display
*List of measuring points
Bar harts
Line diagram
_____________________
Menu1 PROGRAMMING-Menus
Menu2 ASSISTANT-Menus
POFF *ON F MENU1 MENU2
* ALMEMO 2690-8 *
±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
PROGRAMMING-Menus:
Times, y les
Re ording to memory ©
Output from memory
Sensor programming
...Spe ial fun tions
Devi e onfiguration
Output modules
Power supply
_____________________
Menu1 ASSISTANT-Menus
Menu2 MEASURING-Menus
POFF *ON F MENU1 MENU2
* ALMEMO 2690-8 *
±±±±±±±±± ±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
ASSISTANT-Menus:
Start-Stop
Averaging ©
Volume flow
Fun tion hannels
S aling
Sensor adjustment
Limits, Alarm
Analog output
Thermal oeffi ient
Wet bulb globe temperature
±±±±±±±±± ±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±±
Menu1 MEASURING-Menus
Menu2 PROGRAMMIER-Menus
POFF *ON F MENU1 MENU2

Function Keys
8.2 Function Keys
The function of the keys F1 to F4 (6) can
be different in the various menus. It is indica-
ted by abbreviations in the bottom line of the
display (soft keys). In the manual the soft key
abbreviations are set in angle brackets, e.g.
<START> .
Next to the meas. value, control symbols
for the meas.value are displayed (s. below).
The following keys are available in the Stan-
dard display (s.r.) :
Selection of measuring points with the cursor keys (6)  o.  ...
Starting a cyclic measurement <START> or F1
Stopping a cyclic measurement < STOP > or F1
Single manual output/storage of all measured values < MANU > or F2
Output of menu functions via the interface < PRINT > or F3
Returning back to the menu selection < ESC > or F4
8.3 Control Symbols
Symbols for monitoring the state of the device in the status line:
Continuous measuring point scan: C
Measurement stopped or started: ll or ©
Measuring point scan started including storing: REC
Measuring point scan started incl. output via interface: COM
Start/end time of measurement is programmed: l© or ©l
Relay status (external output module) off or on: R-- or R01
Display illumination switched on or pause: * or *
Batt./accumulator charge tate:100% charged, 50% charged, di charged: ´´´´´´´´¶ , ´´´´´µµµµ¶ , ´µµµµµµµµ¶ fla he
Symbols for checking the measured value (see above)
No sensor, measuring point deactivated: ´-----´
Measured value altered by sensor correction or scaling: º
Averaging in progress: »
Output function altered (s. 10.4. ): D , H , L , M , A
Exceeding of limit value Max or Min: s or t flashes
Exceeding of measuring range: display of max. value O flashes
Undershooting of meas. range: display of min. value U flashes
Sensor breakage sensor voltage Lo :display -.-.- B flashes / L flashes
Supply voltage too low for measurement: display switched off
ALMEMO® 2690-8 19
F1 F2 | F3 F4
C © REC COM l© ©l R01 * ´´´´´´µµµµ¶
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
01: Velo ity m/s
æ » H º
28.67
Maximum value: 31.34 mls
Minimum value: 25.37 mls
Cy le-timer: 00:02:30 Un
Memory free: 512.0 kB
START MANU M PRINT ESC

8. Display and Keypad
8.4 Function Selection
Each menu consists of a number of func-
tions that, possibly, have to be used or
programmed during operation.
Help window at function selection:
Selection of the functions.
First changeable parameter is highlighted PROG
as inverse coloured font on a black bar: Velo ity
In the middle of the softkey line appears for control: F
Switching to the next function:  or  ...
Depending on the functions, the keys F1 or F3
provide corresponding functions, e.g. MaxValue Clear <CLR>
Meas. value Set to zero, Meas. value Adjust <ZERO> / <ADJ> , PROG
Memory data output <PRINT>
Memory Clear <CMEM>
8.5 Data Entry
If a programmable parameter is selected (s. 8.4) you can enter or clear the va-
lue.
Clearing the programmed values < CLR >
For programming, press the key PROG
Then you are in the input mode P in the middle of the oftkey line
the cursor flashes below the first cursor position Cy le-Timer: 00:00:00
Increasing the selected number with  ...
Decreasing the selected number with  ...
Changing the sign of numerical values < +/- >
Selecting the next position 
the cursor flashes below the second digit Cy le-Timer: 00:00:00
Switching back to the previous digit 
Each digit is programmed analogously to the first one  /  ..., 
Quitting the data entry PROG
Cancelling the programming process <ESC>
The input of letters, measuring ranges etc. can be carried out accordingly.
20 ALMEMO 2690-8
C © REC COM l© ©l R01 * ´´´´´´µµµµ¶
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
01: Velo ity m/s
æ » H º
28.67
Maximum value: 31.34 mls
Minimum value: 25.37 mls
Cy le-timer: 00:02:30 Un
Memory free: 512.0 kB
ZERO ADJ M ESC
To set measured value to
zero, press key: ZERO
To adjust sensor
in zero point (slope)
press key: ADJ