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iM871A Wireless M-Bus 

User Manual 

 

 

 

 
 

Document ID:

 4100/6404/0048 

 
 

IMST GmbH 

 

Carl-Friedrich-Gauß-Str. 2-4 

 

47475 KAMP-LINTFORT 

 

GERMANY 

Summary of Contents for iM871A

Page 1: ...iM871A Wireless M Bus User Manual Document ID 4100 6404 0048 IMST GmbH Carl Friedrich Gauß Str 2 4 47475 KAMP LINTFORT GERMANY ...

Page 2: ...Version 1 0 Added chapter USB Stick 1 1 Added AES encryption 1 2 C Mode added Aim of this Document This document is intended to provide help using the iM871A Wireless M Bus module It gives an overview about its features and the Wireless M Bus Stack It explains how to control the module by a connected host controller This user manual includes the basic hardware specifications and describes how to p...

Page 3: ...s 14 3 2 2 Host Controller Protocol 14 3 2 3 General Device Functions 14 3 2 4 Device Configuration 15 3 2 5 Operation Modes 16 3 2 6 Real Time Clock Support 16 3 2 7 AES 128 Encryption Decryption 17 3 3 Low Power and Wake up 17 3 3 1 Auto Power Saving 17 3 4 Port Pin Signaling 17 4 MODULE SPECIFICATION 18 4 1 General Radio Settings 18 4 1 1 Channel Setup 18 4 1 2 Power Level Setup 18 4 1 3 Data R...

Page 4: ...nterface 23 5 2 USB Stick 24 5 2 1 USB Driver 24 5 3 Configuration with WM Bus Studio 25 6 ORDERING INFORMATION 26 7 APPENDIX 27 7 1 List of Abbreviations 27 7 2 List of Figures 28 7 3 List of Tables 28 7 4 References 29 8 REGULATORY COMPLIANCE INFORMATION 30 9 IMPORTANT NOTICE 31 9 1 Disclaimer 31 9 2 Contact Information 31 ...

Page 5: ...battery powered devices like water and gas meters The pre certified module provides a serial interface as well as analog and digital inputs and outputs and can easily be integrated into a meter With its integrated Wireless M Bus protocol stack it will reduce the development time and cost The iM871A can achieve a link budget up to 123 dB resulting in exceptional RF range and communication performan...

Page 6: ...ations The iM871A wireless M Bus module offers a cost effective RF solution for smart metering applications connecting water heat electricity and gas meters with data concentrators in the 868 MHz frequency band Electricity meters Gas water and heat meters Data concentrators and readers Automatic meter reading AMR ...

Page 7: ... Studio the features can easily be explored The module can either be used as WM Bus modem or can be taken as stand alone solution on request Figure 2 1 iM871A Metering Application Example with Host Controller Figure 2 2 iM871A Metering Application Example Stand Alone Metering Hardware Host Controller Metering Application WM Bus Application Layer Interface Driver UART iM871A Wireless M Bus Stack Ho...

Page 8: ...ontroller Interface HCI The wakeup can also be done over the serial interface Moreover the iM871A provides the opportunity to enter one of the power save modes automatically after a successful WM Bus packet transmission Supported Device Modes The iM871A is designed for metering applications Meter Mode but it also can operate in Other Mode Concentrator Data Collector etc Operation and State Indicat...

Page 9: ...ir traffic into a log file Radio Link Test The iM871A offers the possibility to evaluate the radio link quality between two devices with the Radio Link Test During this test a configurable number of packets including a TX packet counter is sent from a local device which is connected to the WM Bus Studio to a peer device The peer device returns the number of received packets back to the sender Wire...

Page 10: ...r Figure 3 1 iM871A WM Bus Stack 3 1 1 General The Wireless M Bus protocol stack implemented on iM871A is compliant the European standard 13757 part 4 Communication systems for meters and remote reading of meters 1 It describes the wireless communication of water heat electricity and gas meters with data concentrators For sake of convenience in this manual such meter devices are called meter the c...

Page 11: ...kcps 3 out of 6 868 95 MHz 56 chips T2 Meter Other 100 kcps 3 out of 6 868 95 MHz 56 chips Other Meter 32 768 kcps Manchester 868 3 MHz 56 chips R2 Meter Other 4 8 kcps Manchester 868 03 MHz n 60 kHz 104 chips Other Meter 4 8 kcps Manchester 868 33 MHz 104 chips C1 Meter Other 100 kcps NRZ 868 95 MHz 64 chips C2 Meter Other 100 kcps NRZ 868 95 MHz 64 chips Other Meter 50 kcps NRZ 869 525 MHz 64 ch...

Page 12: ...unidirectional compact operation Mode C2 bidirectional compact operation Transmission at 868 95 MHz chip rate 100 kcps encoding NRZ Receiving meter at 869 525 MHz chip rate 50 kcps decoding NRZ Telegram Format A Telegram Format B Note The iM871A can be used as RF Adapter for Wireless M Bus devices It provides the physical access to the Wireless M Bus Network For complete Wireless M Bus protocol op...

Page 13: ... a synchronization word The length of these fields is mode dependent The implementation is done according to EN13757 4 1 The postamble contains normally 8 chips Only for even packet sizes in T mode Meter the postamble consists of four chips Block 1 L Field Address Type Version 1 byte 4 bytes 1 byte 1 byte 6 bytes 1 byte C Field M Field A Field 2 bytes CRC Field 2 bytes Figure 3 3 Wireless M Bus Te...

Page 14: ...re 3 6 Wireless M Bus Telegram Format B Block 1 L Field 1 byte 6 bytes 1 byte C Field M Field A Field 2 bytes Figure 3 7 Wireless M Bus Telegram Format B block1 header The first byte of block 1 is the length byte It describes the number of all following bytes including the CRC bytes The block 1 in Telegram Format B is the same as in Telegram Format A only the CRC Field is missing Block 2 CI Field ...

Page 15: ...e user is able to connect the iM871A radio module to a host system It can be used for configuration data exchange and device control Each message to or from the radio module is embedded in a specific message frame SOF Control Field MsgID Field Length Field Payload Field CRC16 8 Bit 8 Bit 8 Bit 8 Bit n 8 Bit 16 Bit Msg Header Field 24 Bit Figure 3 10 Message format on serial interface 3 2 3 General...

Page 16: ...ID Block 1 4 byte Device Identification A Field 0x12345678 4 byte Device Identification A Field USB Stick Variant pre configured address Version Block 1 1 byte Version A Field 0x01 Device Type Block 1 1 byte Device Type A Field 0x00 Radio Channel R Mode channel 1 Radio Power Level Transmission power 13 RX Window Receive time after transmission in ms Meter only 50 Power Saving Mode Enable disable a...

Page 17: ...eration modes enables the device to align its behaviour according to a given use case e g test mode application mode The system operation mode is determined during firmware start up and requires a reset to get changed Get System Operation Mode This function returns the current System Operation Mode Set System Operation Mode The following System Operation Modes are supported Application Mode Hardwa...

Page 18: ...an be woken up again by sending a new HCI command 3 3 1 Auto Power Saving For devices which are configured to operate in Meter mode the feature Auto Power Saving can be enabled Automatic Power Saving means that the device enters the configured power saving mode automatically when a WM Bus message was sent The next command on the serial interface will wake up the device For devices operation in Oth...

Page 19: ...posite direction is always done in 868 33 MHz channel 5 Channel Frequency MHz 1 868 09 2 868 15 3 868 21 4 868 27 5 868 33 6 868 39 7 868 45 8 868 51 Table 4 1 Possible Frequency Channel Settings in R Mode 4 1 2 Power Level Setup Table 4 2 shows the possible power level setup relating to the 50 connector pin ANT Power Level TX power dBm Description 0 8 Minimum output power 1 5 2 2 3 1 4 4 5 7 6 10...

Page 20: ...te results in a data rate of 66 66 kbps 3 out of 6 coding chip rate data rate NRZ coding Table 4 3 Possible RF Data Rates 4 2 System Timing 4 2 1 Wake up after Low Power Mode Figure 4 1 shows the timing diagram of the transmission of a 42 byte WM Bus packet in S Mode The device is in Low Power Mode and is woken up by the edge of the first UART bit that is received from the host controller After su...

Page 21: ...less M Bus Module Specification iM871A_WMBus_UserManual docx Wireless Solutions v1 2 Page 20 Figure 4 2 shows the time gap between the RX signal and the wake up indication Figure 4 2 Packet Timing after Wake up detailed view ...

Page 22: ...vice that is triggered by the host controller to transmit a Wireless M Bus packet every 2 seconds After transmission the meter is able to receive commands from a master device concentrator data collector etc The rest of the time the meter remains in Low Power Mode µC RX T X 4mA 21mA 38mA RX Window 100nA µC RX T X RX Window Low Power Mode RTC off Low Power Mode RTC off 1s 2s 3s Figure 4 3 Current C...

Page 23: ...nted on The Demo Boards offer several often used peripherals like e g buttons and LEDs The module can easily be accessed via the on board FTDI RS232 to USB converter Figure 5 1 gives an overview of the Demo Board and its peripherals Figure 5 1 Demo Board Using the Demo Board with the iM871A it must be soldered on its specific adapter board and plugged into X1 and X2 Now all necessary module pins a...

Page 24: ...A is powered on Additionally LED 5 is turned on if a USB connection to a PC is established It is recommended either to use the battery or the USB power thus S1 can be used as on off switch To supply the radio module with power jumper JP1 must be set Power supply of the iM871A except the USB interface and the attached radio module is interrupted if push button B4 is pressed Because the radio module...

Page 25: ...host system The iM871A USB Stick is not part of the Wireless M Bus Starter Kit it has to be ordered separately 5 2 1 USB Driver Before the USB interface can be used for the first time the desired hardware driver for the USB controller must be installed on the PC If the PC will detect the USB Stick as new hardware please follow the given instructions to install the new virtual COM port The USB Stic...

Page 26: ... the capabilities of the iM871A The GUI offers a comfortable way to configure and control some features of the embedded Wireless M Bus Stack like Wireless M Bus Modes RF Message Header Configuration Radio Configuration Automatic Power Saving Embedded Radio Link Test RF Message Generator Real Time Clock Support AES Keys Figure 5 3 Wireless M Bus Studio Note For detailed information please refer the...

Page 27: ...tributor iM871A Radio module iM871A wimod imst de SK iM871A Starter Kit for the iM871A See Notes wimod imst de AB iM871A 2x Adapter Board with iM871A wimod imst de iM871A USB USB Stick with module iM871A wimod imst de Notes The Starter Kit contains two Demo Boards two Adapter Boards with iM871A two antennas batteries and a CD with documentation Table 6 1 Ordering Information ...

Page 28: ...namic Link Library GUI Graphical User Interface HCI Host Controller Interface MCU Microcontroller Unit PCB Printed Circuit Board PER Packet Error Rate RAM Random Access Memory RF Radio Frequency RSSI Received Signal Strength Indication RTC Real Time Clock SMD Surface mounted device SPI Serial Peripheral Interface SRD Short Range Devices UART Universal Asynchronous Receiver Transmitter USB Universa...

Page 29: ...at B 13 Figure 3 7 Wireless M Bus Telegram Format B block1 header 13 Figure 3 8 Wireless M Bus Telegram Format B block2 13 Figure 3 9 Wireless M Bus Telegram Format B block3 13 Figure 3 10 Message format on serial interface 14 Figure 4 1 Packet Timing after Wake up 19 Figure 4 2 Packet Timing after Wake up detailed view 20 Figure 4 3 Current Consumption 21 Figure 5 1 Demo Board 22 Figure 5 2 iM871...

Page 30: ...ppendix iM871A_WMBus_UserManual docx Wireless Solutions v1 2 Page 29 7 4 References 1 EN13575 4 2011 Communication systems for meters and remote reading of meters 2 WM Bus Studio User Manual 3 iM871A HCI Specification 4 iM871A Datasheet ...

Page 31: ...ned to be embedded into other products referred as final products According to the R TTE directive the declaration of compliance with essential requirements of the R TTE directive is within the responsibility of the manufacturer of the final product A declaration of conformity for the radio module is available from IMST GmbH on request The applicable regulation requirements are subject to change I...

Page 32: ...ystems or units in which products from IMST GmbH are integrated with applicable legal regulations Customers should provide adequate design and operating safeguards to minimize the risks associated with customer products and applications The products are not approved for use in life supporting systems or other systems whose malfunction could result in personal injury to the user Customers using the...

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