Wurth Elektronik ANR001 User manual
ANR001
METIS-II REPEATER MODE
VERSION 1.4
JULY 19, 2023
WIRELESS CONNECTIVITY & SENSORS
ANR001 - Metis-II Repeater Mode
Revision history
Manual
version
FW
version
HW
version Notes Date
1.0 2.8.0 2.0 •Initial version November 2018
1.1 2.8.0 2.0
•Updated file name to new
AppNote name structure. Updated
important notes, legal notice &
license terms chapters.
June 2019
1.2 2.8.0 2.0
•Updated address of Division
Wireless Connectivity & Sensors
location
October 2019
1.3 2.8.0 2.0 •Corrected typo’s November 2020
1.4 2.8.0 2.0 •Updated
Important notes
, meta
data and document style
July 2023
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ANR001 - Metis-II Repeater Mode
Contents
1 Introduction 3
2 Motivation 3
3 Using the included wireless M-BUS repeater 5
3.1 Configuration using CMD_SET_REQ . . . . . . . . . . . . . . . . . . . . . . . . 7
3.2 Supported wireless M-BUS modes for the repeater . . . . . . . . . . . . . . . . 9
3.3 Energyconsumption ................................. 9
4 CMD_RP_DATA_IND 10
4.1 Example1....................................... 10
5 Duty cycle requirements 11
6 Important notes 12
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ANR001 - Metis-II Repeater Mode
1 Introduction
Starting with firmware version 2.8.0 the Metis-II include a feature to enable receiving, buffering,
delaying and forwarding radio frames better known as single-hop unidirectional repeater func-
tionality.
WE order code Former order code Description
260702118300x AMB8626-M-TR 868 MHz wM-BUS module 14dBm, T&R,
Firmware 2.7.0
2607021183010 AMB8626-M-RP-TR 868 MHz wM-BUS module 14dBm, T&R,
Firmware 2.8.0
Table 1: Metis-II Ordering information
The European Standard EN13757 and the OMS Group Specification give information on how
a single-hop unidirectional repeater shall be implemented and what radio frames shall be sup-
ported by the repeater.
Our implementation will enable the repeater mode only on a very specific configuration set of
the wM-Bus module as introduced later.
Using the repeater mode requires careful attention of the user regarding local
regulatory requirements. Especially the duty cycle requirements need to be
adhered to.
For example by realizing a suiting host implementation in the user’s end system
that implements duty cycle restriction.
2 Motivation
By means of the repeater mode a module or USB stick can be utilized to enhance the effec-
tive radio range of wireless M-BUS meters within the repeater’s range. This will happen for
frames that follow EN13757-3:2013 and EN13757-4:2013 as well as OMS Specification Vol-
ume 2 Generation 4 V4.1.2. In essence this applies to all wM-BUS frames that have a hop
counter field at a location described in the standard and also have a C-Field of either SND-NR
or SND-IR, which are only to be used in direction meter to other (uplink).
As the size of the hop counter field is limited to 1 bit it is not possible to provide multiple hops
in a standard compliant way. Therefore the hop counter must be ’0’ in the received frame and
will be set to ’1’ by the repeater to indicate that the message was repeated.
A frame already having the hop counter ’1’ when being received by a repeater will be discarded.
To be able to find the hop counter inside a frame the repeater parses and checks parts of the
radio frame upon reception. Currently the following frame structures and conditions are imple-
mented in the firmware, listed in the order of priority they will be tested and applied:
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•Frames that have an Extended Link Layer (ELL) as first Control Information Field (Ci-
Field). This ELL has a Communication Control Field (CC-Field) which provides a Hop
Count Subfield (H-Field). The first Ci-Field can be followed by one or multiple further
Ci-Field(s).
•Frames that have exactly one Ci-Field in the entire frame, indicating either a "short data
header" or a "long data header", with encryption modes in the Configuration Field being
either 0 or 5 and the Configuration field providing a hop counter at a well-known location
within the field.
Note: Encryption mode 0 is not described in the standard but from our experience with
different manufacturers mode 0 is used by them with the same structure as mode 5. This
means the Configuration Field Bit 0 is the Hop Counter Field.
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3 Using the included wireless M-BUS repeater
The repeater mode runs in parallel to the normal module functions as sending and receiving
frames without interfering the normal operations of the module or the reachability of the module
via UART. To archive this, the frames to be repeated are queued in a non-shared buffer so the
normal shared buffer is not blocked by the repeater.
The repeater mode is enabled by setting the UserSetting (US) parameter
Repeater_Enable
at index 82 (0x52) from 0x00 (= disabled) to 0x01 (= enabled) via the
CMD_SET_REQ
as shown
below in the example configuration in chapter
3.1
.
But even though this enables the repeater mode of the module there are further configurations
required for the activation to take effect.
Please refer to the wM-Bus module user manual or the following example sec-
tion on how to use
CMD_SET_REQ
and
CMD_GET_REQ
commands accordingly.
If any of the parameters or requirements are not fulfilled the unidirectional re-
peater functionality may cause critical malfunctions of the module.
The following table shows the UserSetting parameters to configure the module as a repeater:
US Parameter Required value US Offset
UART_CTL0
0x00 0x00
UART_CTL1
0x80 0x01
UART_BR0
0x34 0x02
UART_BR1
0x00 0x03
UART_MCTL
0x20 0x04
UART_CMD_Out_Enabled
0x01 (enabled) 0x05
APP_AES_Enable
0x00 (disabled) 0x0B
MBUS_B1_ADD_Disable
0x01 (disabled) 0x30
RF_AutoSleep
0x00 (disabled) 0x3F
Mode_Preselect
0x03 or 0x08 or 0x09 or 0x0E 0x46
Repeater_Enable
0x01 (enabled) 0x52
Table 2: UserSettings Requirements
An additional requirement is that no frame preloading shall be used when the repeater mode
is enabled. If the preloading is or was used since the latest restart of the module the user is
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ANR001 - Metis-II Repeater Mode
required to use the
CMD_DATA_CLR_PRELOAD_REQ
command (
0xFF 31 00 CE
) in order to clear
the preloaded frame from the queue.
Preloading is obsolete since firmware version 2.8.0 and shall not be used any-
more.
The command
CMD_SET_MODE_REQ
shall never be used when the repeater mode is active. Doing
so will disable the repeater function.
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3.1 Configuration using CMD_SET_REQ
By using the following
CMD_SET_REQ
sequence followed by a
CMD_RESET_REQ
the settings to
enable the repeater mode will be applied to the non-volatile memory of the module.
Because of the nature of the firmware design radio packets have the highest
priority in the shared buffer. Please perform such setting sequences only in non
radio polluted environments or by using the ACC PC Software.
You are encouraged to check the currently configured values by using
CMD_GET_REQ
before us-
ing a
CMD_SET_REQ
to avoid unnecessary flash erase/write cycles as this resource is limited by
the hardware.
First check the firmware version of the module by executing
CMD_GET_FWVERSION_REQ
(
0xFF 0C
00 F3
). If the response indicates firmware version 2.8.0 (
0x02 08 00
) or higher you are good
to proceed.
If you still have an old firmware version use ACC to update to the most recent firmware before
proceeding.
Revert to factory defaults
CMD_FACTORYRESET_REQ: 0xFF 11 00 EE
All UserSettings are reverted to factory defaults.
Restart module to apply factory defaults
CMD_RESET_REQ: 0xFF 05 00 FA
The Factory defaults are loaded into RuntimeSettings, the UART is now using 9600 Baud 8n1.
Please adjust the UART baudrate of your host to 9600 Baud after the reset to
be able to still communicate with the module.
Set the UART speed to 115200 Baud 8n1
CMD_SETUARTSPEED_REQ: 0xFF 10 01 07 E9
All UART speed related UserSettings are updated by this command accordingly.
Factory default: 9600 Baud 8n1
Revert to factory defaults
CMD_RESET_REQ: 0xFF 05 00 FA
The UART baudrate is now using 115200 Baud 8n1.
Please adjust the UART baudrate of your host to 115200 Baud after the reset
to be able to still communicate with the module.
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Set the Mode_Preselect to either S2 or C2_T2_Other
For using S2 mode a reconfiguration is not required.
For C2_T2_Other mode use
CMD_SET_REQ: 0xFF 09 03 46 01 09 BB
Factory default: S2 mode
Enable Command Output mode
CMD_SET_REQ: 0xFF 09 03 05 01 01 F0
Factory default: disabled
Your host needs to implement the Command Interface as specified in the wM-
BUS manual plus the additional command
CMD_RP_DATA_IND
defined in chap-
ter
4
in this document.
Enable repeater mode
CMD_SET_REQ: 0xFF 09 03 52 01 01 A7
Factory default: disabled
Reset module
CMD_RESET_REQ: 0xFF 05 00 FA
This will reset the module and activate the settings done above.
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3.2 Supported wireless M-BUS modes for the repeater
The single-hop unidirectional repeater requires to receive radio frames. For example all wM-
BUS modes containing a "1" are send-only modes and can therefore not be used when the
repeater mode shall be enabled.
Thus we limited the wM-BUS modes to the following set to provide the functionality of the
repeater mode.
•S2 mode, Mode_Preselect value 0x03
•T2-Other mode, Mode_Preselect value 0x08
•C2-T2-Other mode, Mode_Preselect value 0x09
•C2-Other mode, Mode_Preselect value 0x0E
By using these modes the repeater receives as if it would be a data collector or Smart Meter
Gateway and repeats the frames as if it would be a meter, so that the repeated frames (with hop
counter changed to ’1’) can be received by other data collectors and Smart Meter Gateways.
3.3 Energy consumption
By its very nature the repeater has the radio receive mode activated permanently when not
sending a frame. In regard to a battery operated device this means that the battery will be
drained quite fast. The typical RX current is around 30 mA and the typical TX current is around
53 mA.
Therefore the recommendation for a repeater is to be used in mains-powered devices and
products only.
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4 CMD_RP_DATA_IND
This UART frame will indicate towards the host that a frame was successfully repeated.
4.1 Example 1
The indication will share further parameters that can be used by the host system to trace the
utilization of the buffers as well as to trace the duty cycle used by the repeater mode. The 1
byte buffer ID is an unsigned buffer index number indicating which internal buffer of the module
the repeated frame was using.
The 2 byte parameter duration states the TX duration in milliseconds of the repeated frame
which successful transmission is indicated by this indication message. The module calculates
this value dependent on the wireless M-BUS mode, radio frame length and frame format used
to repeat this frame.
CS is as usual in the command mode the XOR concatenation of all preceding bytes starting
with the start signal 0xFF.
start signal command length buffer ID duration CS
0xFF 0x07 0x03 <buf ID> <LSB, MSB> <cs>
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5 Duty cycle requirements
Citation from ETSI EN 300 220-1 V3.1.1 (Feb 2017) chapter 5.4.1, which is required to conform
to the RED and CE, at the time this Application Note was written:
Duty cycle is the ratio expressed as a percentage, of the cumulative duration of transmissions
Ton_cum within an observation interval Tobs .DC =Ton_cum
Tobs Fobs
on an observation bandwidth
Fobs. Unless otherwise specified, Tobs is 1 hour and the observation bandwidth Fobs is the op-
erational frequency band. Each transmission consists of an RF emission, or sequence of RF
emissions separated by intervals < TDis.
The manufacturer of the end product has sole and ultimate responsibility for the
conformity of the end product to the applicable directives, whether he designed
and manufactured the product himself or is considered as a manufacturer be-
cause the product is placed on the market "under his name".
The following table shows the duty cycle for the frequency bands supported by our 868 MHz
wireless M-BUS modules. The wireless M-BUS standard does specify the channel access to
be random. But it does not not specify to implement any channel access methods and due to
timing parameters this would cause a EN13757 compliance problems. Thus polite spectrum
accesss (PSA) of the RED cannot be applied to increase the duty cycle.
For the repeater functionality only the role "meter to other" is used for TX operations.
wM-BUS mode wM-BUS role Frequency Duty cycle Time per hour
S meter to other 868.300 MHz 1 % 36s
S other to meter 868.300MHz 1 % 36s
T meter to other 869.950 MHz 0.1 % 3.6s
T other to meter 868.300 MHz 1 % 36s
C meter to other 869.950 MHz 0.1 % 3.6s
C other to meter 869.525 MHz 10 % 360s
Table 3: Duty cycle as required by ETSI EN 300 200-2 V3.1.1 for all wM-BUS modes in 868
MHz Bands
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6 Important notes
The Application Note and its containing information ("Information") is based on Würth Elek-
tronik eiSos GmbH & Co. KG and its subsidiaries and affiliates ("WE eiSos") knowledge and
experience of typical requirements concerning these areas. It serves as general guidance and
shall not be construed as a commitment for the suitability for customer applications by WE
eiSos. While WE eiSos has used reasonable efforts to ensure the accuracy of the Information,
WE eiSos does not guarantee that the Information is error-free, nor makes any other repre-
sentation, warranty or guarantee that the Information is completely accurate or up-to-date. The
Information is subject to change without notice. To the extent permitted by law, the Information
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WE eiSos is not liable for application assistance of any kind. Customer may use WE eiSos’
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List of Figures
List of Tables
1 Metis-II Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 UserSettings Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Duty cycle as required by ETSI EN 300 200-2 V3.1.1 for all wM-BUS modes in
868MHzBands .................................... 11
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Contact
Würth Elektronik eiSos GmbH & Co. KG
Division Wireless Connectivity & Sensors
Max-Eyth-Straße 1
74638 Waldenburg
Germany
Tel.: +49 651 99355-0
Fax.: +49 651 99355-69
www.we-online.com/wireless-connectivity
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