LKM LKM75X User guide
Handbuch zu den Komponenten des Systems
März 2017
Manual relating to the system components
March 2017
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The radio system type LKM75x
Table of contents
1. General
2. International standard IEE 802.15.4
3. Receiver LKM751
4. Analogue unit LKM752
5. Transmitter EEPROM
6. Transmitter with I2C-bus LKM753
7. Radio transmitter LKM754
8. The program WPAN868
9. Appendix 1
Interface protocol USB and RS485 (not Modbus)
10.Appendix 2
Terminal assignment of the receiver LKM751
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1. General
The radio system type 75X is a system designed for transmitting physical quantities
as, for example, temperature, moisture, light intensity and pressure. The sensors
used are partly compatible with our multi measuring device type DTM 4000, and they
can also be employed in systems like Rasberry and Co. It has a very flexible
structure and can easily be extended to other sizes. Several digital and analogue
channels are available for evaluation purposes. The transmitters are powered by
batteries which, depending on the transmission frequency, have a lifetime of about 2
years.
The devices operate in the licence-free frequency band of 868/915MHZ, thus also
covering the American frequency band. The permitted transmission capacity enables
distances up to 500 m to be bridged.
2. International standard IEE 802.15.4
The standard IEE 802.15.4 has been developed for the installation of low-power
radio networks for the short-range radio data transmission, and serves particularly to
automate the industrial and building technology. The development started
approximately in the year 2000.
The standard describes the bit transmission layer (layer 1, PHY-layer and the data
link layer, layer 2, MAC- layer). The ZigBee-protocol is also based on this standard.
The transmission band is split up into several channels. If needed, the user can
switch between them. The data transmission takes place primarily in the licence-free
868 MHz band (Europe, Asia), and in the 2.4 GHz-band (worldwide).
The radio system type LKM75X operates in the 868/915MHz-band.
2.1 Structure of the system
Each transmitter is identified via an IEEE-number. This number is firmly assigned by
the manufacturer of the modules. For identifying the network, the PAN-ID must be
applied. It is fixed in the receiver, however, it is possible to change it. Before a
transmitter is put into operation, it has to be told –via the WPAN868 software –with
which PAN-ID it is allowed to register. Thus, during each transmission, the IEEE-
number, the PAN-ID, the kind of the transmitted data (temperature,
temperature/moisture, light), and the corresponding values are sent. In the Appendix,
the structure of the protocol which is output by the receiver via the interface is shown.
If no PAN-ID is input into the transmitter, the PAN-ID 0x1000 is used. However, the
data transmission can also take place via transmitters located in the network,
provided they are supplied with sufficient energy. In this case, routing will be
automatically effected.
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3. Receiver LKM751
3.1 General
The receiver is mounted in a standard rail housing and supplied with 24 V. It is
provided with several serial interfaces. The LKM751 device is able to communicate
with other components via a bus system which is integrated in the rail. At present,
this is the analogue unit. No external connections are required any more.
Furthermore, the receiver is equipped with an illuminated LCD which allows the
values of 2 or 4 channels to be displayed. The display mode is configured via the
software. Figure 3.1 shows the position of the various function elements. If the
jumper for the write protection of the EEPROM is removed, the existing
configuration cannot be overwritten any more!
3.2 USB interface
The receiver is provided with a mini-USB interface by means of which it can be
configured, and the data can be read out. A corresponding program developed for
these tasks, as well as a suitable cable are supplied with each receiver. These
programs are described separately. The structure of the data sets is shown in the
Appendix. The USB interface enables the receiver to be supplied with voltage, too.
However, the analogue unit cannot be operated with it.
3.3 RS485 interface
This interface allows the data to be transmitted over longer distances. In addition,
also other evaluation units (PLC etc.) can be connected. This interface is also
designed as Modbus interface (switchable via software). Some more detailed
information can be found in the Modbus manual.
3.4 LCD
The LCD is backlit. Up to 4 measuring values can be displayed. The first four
registered transmitters are automatically displayed. Via the WPAN686 program, the
user may fix whether 2 or 4 values are displayed.
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3.5 Alarm-/Low battery relay
The receiver includes 2 potential-free semi-conductor relays whose contacts are led
out. They can arbitrarily be interconnected. The LowBat-control is triggered when the
battery voltage of one of the registered transmitters falls below 2.7 V. Thus, also in
small autonomous systems a signal can be released to inform the user about an
incident to be counteracted. The alarm relay is an additional option. Up to 4
transmitters can be selected. In case a pre-defined limit value is exceeded, the relay
will be triggered. The relays can cope with a voltage of maximally 60 V and a current
of 0.5 A.
3.6 LED
The receiver also includes 3 LEDs serving the following functions:
LED1 Operation display
LED2 Network available
LED3 Radio signal
LED1 lights up green when the operating voltage is on.
LED2 lights up when at least one receiver is registered.
LED3 flashes briefly when a message is received.
Fig. 3.1
Position of the single objects
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4. Analogue unit LKM752
Up to 2 analogue units can be connected via the internal bus. Each analogue unit
has 4 outputs 0...10V and 4...20mA. A current output and a voltage output
correspond with one another in each case. This means, they operate in the same
measuring range. The measuring range is again set via the WPAN686 program. A
total of up to 8 analogue outputs can be used. Due to its modular structure, the
system is very flexible. The outputs are short-circuit proof. However, it is not allowed
to supply external voltage to them. If 2 analogue modules are coupled, the jumper of
one of them must be removed to allow module recognition.
Fig. 4.1
Analogue module LKM752
5. Transmitter EEPROM
The EEPROM incorporated in the transmitter is of special importance. It saves a
possible offset and also the PAN-ID of the receiver to which the transmitter can log
on. On the circuit board, there is a jumper for write protection. If it is plugged, the
write protection for the EEPROM is unlocked. Now, using the WPAN868 program,
the various values can be configured. At the same time, this jumper prevents the
transmitter from going into sleep mode when being switched on. In other words, the
PC has immediate access to the transmitter without having to wait for the sleep cycle
of the transmitter. Please take care to remove this jumper after setting the values
as the battery will be exhausted after a few days!
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6. Transmitter with I2C-bus LKM753
The LKM753 device is provided with a standard I2C interface. For this, a large
number of sensors are available. So far, we have implemented a temperature sensor
and a combined temperature/moisture sensor. An EEPROM incorporated in the
sensor allows accuracy to be improved drastically. These sensors are also
compatible with our multifunction meter type DTM4000. The sensor type will be
recognized automatically.
As energy source a lithium battery type CR123 is used. The transmission frequency
being 1min, its lifetime will be approximately 2 years. Also, there is the option to
include further sensor types.
Fig. 6.1 Position of the operating
elements
On the circuit board, there are
2 potentiometers which can be used –
according to the sensor - for offset
corrections.
7. Radio transmitter LKM754
The LKM754 device is a programmable transmitter designed for various
thermocouples and resistance sensors.
Fig. 7.1 Position of the operating
elements
The following types can be
implemented:
Thermocouples: K, N, J, T, S, B
Resistance sensors:
Pt100/1000
Depending on the sensor used, various
assignments and jumper positions are
possible.
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Fig. 7.2 Connection possibilities of the various sensors:
In each case, the defined measuring range of the sensor is fully exploited.
8. The WPAN868 program
8.1. General
The WPAN868 program is designed for data acquisition, conversion and evaluation
in connection with the receiver type LKM751. At the same time, a number of various
settings in the receiver just as in the transmitters can be made. A USB cable provided
is used for connecting the PC with the LKM751 device. The various functions are
mentioned and described below.
8.2. Program overview
The overview below shows the structure of the software. Especially in the menu
`Tools` settings for the configuration of the transmitters and the receivers can be
made.
8.3. Menu ´File´
Here, data sets can be loaded and saved. Furthermore, it contains a function for the
export of the data sets into Excel which allows them to be mathematically processed
further.
8.4. Menu ´Process´
In this menu, so-called aliases can be selected. They must consist of a minimum of 3
characters and a maximum of 25 characters, and enable a better recognition of
certain transmitters. After having selected such a name, it is advisable to delete the
protocol and also the evaluations, otherwise a further transmitter will be displayed for
the evaluations.
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8.5. Menu ´View´
Here, for example any lost connections and the list of the aliases assigned under
menu item 8.4 can be displayed.
8.6. Menu ´Options`
Here, it is possible to update the number of the COM-interfaces, to fix the separating
characters for the export into Excel, and to determine the temperature measurement
unit.
8.7. Menu ´Help´
At present, this menu only contains the program version number.
8.8. Menu ´Tools´
In this menu, both transmitters and receivers can be configured. Here, the type of
transmitter is of no importance. The PC must be connected with the respective
device via USB cable, which also provides for the power supply.
8.8.1 Menu ´Configure transmitter´
When the connection with the transmitter is established, the values saved so far are
read out (green lettering). In the bottom row, the desired changes are entered, which
will then appear in the line with the yellow lettering. Here, the measuring time and,
where appropriate, an offset can be set. The lifetime of the battery depends on the
measuring time. Therefore, it should be set as long as it is reasonable for the
application. Furthermore, in the case of the radio transmitters, the sensor type can
be set. Please look at Fig. 7.2. For the I2C-transmitters, this setting option is not
available. In this case, the transmitter is recognized automatically. However, it is also
possible to enter a network PAN-ID here. Now, the transmitter can log on the network
only with this ID.
8.8.2. Menu ´Configure receiver´
When connecting with the receiver, the respective settings are read out and
displayed in green. Under “Settings”, the corresponding parameters can be changed.
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8.8.2.1. PAN-ID/Transmission list/New device
Here, the PAN-ID can be changed.
In addition, the transmitters logged on are displayed. Furthermore, transmitters can
be added or also deleted. Using the corresponding button, all transmitters to be
deleted are selected. Deletion is effected after disconnection. However, it is also
possible to delete some single transmitters by dragging them with the mouse to the
Trash. In this case, they are highlighted in red and deleted from the list after
disconnection. Using another button permits transmitters to be added to the list.
Anyway, the PAN-ID of the network must then have been entered in the transmitter
added. Now, another button can be used to prevent transmitters from being logged
on. Then, the network is closed.
8.8.2.2. Modbus / RS485
The RS485 interface can operate either with our own protocol or with Modbus. Here,
the transmission parameters can also be fixed. If Modbus is set the address (slave
ID) will still have to be selected. Please refer to the Modbus manual.
8.8.2.3. Assignment ModuleAnalogue output
When clicking on this button, a list containing the transmitters logged on opens. Now,
the transmitters can be dragged with the mouse to the corresponding DAC-outputs. If
it is a TF-transmitter, a query is displayed whether the temperature or the moisture
shall be assigned to these DAC. Programming prevents one and the same
transmitter with the same channel (moisture or temperature) from being assigned to
2 DACs. The assignments can be deleted again by moving the respective IEEE-
number of the channel to the Trash. By clicking on “Confirm assignment“, the change
in the settings is transferred to „Changes to be saved”. It comes into effect after
disconnection.
8.8.2.4. Scaling Analogue output
Here, the zero point and the end point must be entered for the single channels. By
pressing OK, this is confirmed for each channel. No moisture values >100 can be
entered. These values are also confirmed after disconnection.
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8.8.2.5. Lost device Interval
In the case of radio systems, it may happen that a message is not received.
However, it is not always desired by the user to get an error message each time this
happens. This function allows the user to fix the time interval between the last radio
contact and the initiation of an error message. By pressing OK, this is confirmed. In
addition, also the type of error message can be determined by using the
corresponding button. After disconnection, the values are again saved.
8.8.2.6. Alarm relay
The receiver is equipped with a semi-conductor relay which permits 4 alarms to be
released in an easy way. When the button is pressed, the list of the transmitters
logged on is displayed. They can now be assigned to the respective alarm module by
means of the Drag and Drop function. The alarm is activated by placing a tick in the
„Alarm“box. In addition, the user can fix whether a moisture or a temperature alarm
shall be released. If the transmitter selected does not have a moisture sensor, a red
exclamation mark is shown after the IEEE number when this number is selected. The
alarm is released if one of the 4 modules reaches the alarm value (or-link). For all
modules together, the user may decide whether the alarm shall be triggered when
the alarm value is either exceeded or when it falls below a certain level. If an IEEE
number of an alarm module is dragged to the Trash, it will be deleted. Clicking on
“Confirm settings”, the data are saved in „Changes to be saved“. They come into
effect by clicking on „Disconnect“.
8.8.2.7. LCD module
Here, it is fixed whether 2 or 4 lines are displayed.
8.9. Language
Here, at present the user can choose between German and English.
8.10. Evaluation
Here, the values of the single transmitters shown in the table can graphically be
represented. Thus, it is well possible to get a quick overview of any trends in the
measurements.
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9. Appendix 1
Interface protocol USB and RS485 (not Modbus)
Byte 0…3 Sensor type
Byte 4…11 IEEE address
Byte 12…13 PAN-ID
Byte 14…22 4xdata à 2Byte
Byte 23 Hop (number of intermediate stations)
Byte 24 Battery status
Byte 25 RSSI (field intensity)
Interface protocol for Modbus
For further information, please refer to the Modbus manual.
Register No.
Assignment
Example
Remarks
xxxx1
Device type transmitter 1
H
0x0000
xxxx2
Device type transmitter 1
L
0x1202
LKM75xFT
xxxx3
IEEE address H1
0x0015
xxxx4
IEEE address L1
0x8d00
xxxx5
IEEE address H0
0x0008
xxxx6
IEEE address L0
0x23CD
xxxx7
PAN ID
0xBAFF
xxxx8
Temperature
0x00EA
23.4°C
xxxx9
Analogue 2
0x0230
In general, the moisture value in the
case of transmitters with SHTxx,
here 56.0% r.h.
xxx10
Analogue 3
0x0000
In general 0, available only in the
case of special transmittes
xxx11
Analogue 4
0x0000
In general 0, available only in the
case of special transmitters
xxx12
Battery/Lost-Connect/ LQI
0x00FF
Battery OK (H) LQI = 255 (L)
xxx13
Reserve
0x0000
xxx14
Reserve
0x0000
xxx15
Reserve
0x0000
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10. Appendix 2
Terminal assignment of the receiver LKM751
Pin Function
1 GND
2 24V
3 B RS485
4 A RS485
5 GND
6 K1.1 Alarm
7 K1.2 Alarm
8 K2.1 Low Battery
9 K2.2 Low Battery
Terminal assignment Analogue unit
10 GND 16 GND
11 I2 17 I4
12 U2 18 U4 IX = 4…20mA
13 U1 19 U3 UX = 0…10V
14 I1 20 I3
15 GND 21 GND
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Notizen:
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Our address:
LKM ELECTRONIC GMBH
Elgersburger Str. 1 Tel.:+49(0)3677/46770
98716 Geraberg Fax.:+49(0)3677/467752
Web.: www.lkmelectronic.de
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Das Funksystem LKM75x
Inhaltsverzeichnis
1. Allgemeines
2. Internationale Norm IEE 802.15.4
3. Empfänger LKM751
4. Analogteil LKM752
5. Sender EEPROM
6. Sender mit I2C-Bus LKM753
7. Funktransmitter LKM754
8. Das Programm WPAN868
9. Anhang 1
Schnittstellenprotokoll USB und RS485 (nicht Modbus)
10.Anhang 2
Anschlussbelegung des Empfängers LKM751
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