3.6 Wireless M-Bus

Wireless M-Bus Interface

This function is only available in 2N^® SmartCom PRO and 2N^® SmartCom PRO ETH, which includes an optional Wireless M-Bus communication module. There are different WM-Bus interfaces according to the module mounted (radio frequency, e.g.). You can define up to 64 meters for which the device will collect readings. Having received a WM-Bus message from a meter defined in the meter list, 2N^® SmartCom PRO will store it into a circular buffer in the internal memory. The stored data can only be retrieved and deleted starting from the oldest record. When the memory is full, the oldest data will be deleted automatically to make space to new records. Define the minimum reading time interval for each meter. Any meter reading coming before the end of this interval will not be stored.

The 868MHz WM-Bus module can work in four modes: T1, S1, C1 and T1+C. The 169MHz module works in the N mode and the 433MHz module in the T1 and C1 modes. They support encrypted messages too in all the modes. In the basic configuration, the terminal does not decrypt messages and stores them as they are received. Enter the correct encryption key and enable decryption to make the messages be decrypted by the module and stored in the decrypted format in the terminal memory. For security reasons, encryption keys are not stored in the memory, but written directly into the module. Therefore, if decryption does not work, check the device transmission and device settings in the terminal and re-enter the encryption key.

Wireless M–Bus Command List 

These commands are implemented in the 2N^® SmartCom PRO unit that is equipped with an optional Wireless M–Bus module.

at^scwmbus="dev_add","MAN",12345678,600,01,07

• This command adds a meter to the meter list. MAN is a three-letter abbreviation of the manufacturer followed by the meter serial number. The next parameter is the minimum interval in seconds between two readings of the meter to be added. If 0 is set, all messages received from the meter are stored. The following two parameters are also necessary for meter identification: Version and Device. Ask the device manufacturer for these values.

at^scwmbus="decrypt",1

• The command enables decryption of the messages received by the module. Setting options: 0 - 1.

at^scwmbus="key_add",1,A5B95C144134DE257AF2ED4F384C7EB7

• The command sets the encryption key for meter 1 in the 32 HEX format.

at^scwmbus="dev_remove",1

• The command removes a meter from the meter list; the parameter gives the meter position in the list (1 - 64).

at^scwmbus="dev_clear"

• The command clears the meter list. 

at^scwmbus="get_oldest"

• The command writes out the oldest record from the Wireless M–Bus meter reading data zone. Example of reply:

^SCDATA: "WMBUS",<timestamp>,<id>,<rssi>,<len>,"<binary data in hexadecimal format>"

Meaning of the parameters:

• timestamp – record receiving time (UNIX timestamp).
• id – record id in the circular buffer.
• rssi – signal strength at message reception in dBm.
• len – message length in bytes.

at^scwmbus="get_oldest"<,n>

• The command provides bulk message reading. The optional n parameter defines how many of the last messages shall be read.

at^scwmbus="del_oldest"

• The command deletes the oldest record from the Wireless M–Bus meter reading data zone to allow you to read the next record using the "get_oldest" function.

at^scwmbus="del_oldest"<,n>

• The command provides bulk message deletion. The optional n parameter defines how many of the last messages shall be deleted.

at^scwmbus="del_all"

• The command deletes all records from the Wireless M–Bus meter reading data zone.

at^scwmbus="mode",11

• The command sets the working mode for the device:
  
  • 1 - T1
  • 3 - S1
  • 8 - C1
  • 11 - T1+C
  • 17 - N1

at^scwmbus="get_space"

• The command displays free memory space for WM-Bus message storing.

at^scwmbus="mess_cnt"

• The command displays the count of the WM-Bus messages received. 

at^scwmbus="RF_channel",1

• The parameter defines the WM-Bus transmission channel. Setting options: 1 - 10.

at^scwmbus="preamble_len",0

• The parameter specifies the framework format: 0 - means 4 (short) / Frame format A. 1 - 70 (long) / Frame format A. 

at^scwmbus="Install_mode",0

• The parameter selects the normal/filter off mode. Normal means that it is necessary to define the modules from which data can be received. All the other modules will be ignored. Filter off means that the module receives and stores all data captured, even those from the modules that are not defined.
  0 - normal.  2 - filter off.

at^scwmbus="restart"

• The command restarts the WM-Bus module.

at^scwmbus="sniff"

• The command switches the WM-Bus module into the sniff mode to capture all messages from the devices in the vicinity and display them in the console. When the command is entered, the connect message is displayed and the terminal starts writing out all the messages. Click Enter to quit. Disconnect is displayed for confirmation, The displayed message looks as follows:

at^scwmbus="sniff"<br>
CONNECT<br>
^SCWMBUS: "AMB",54001477,01,37,-1,-92dBm

The message format and meanings of the elements are as follows: ^SCWMBUS: "MAN",12345678,VER,DEV,ID,SIGNAL

• MAN - manufacturer.
• 12345678 - device serial number.
• VER - meter version given by the manufacturer.
• DEV - quantity to be measured (water / gas) as given by the manufacturer.
• ID - ID in the terminal meter list; if no ID is assigned, the meter is not configured in the terminal and -1 is displayed.
• SIGNAL - signal level at message reception.

at^scwmbus="module_type"

• The command displays information on the WM-Bus module. Example of reply: ^SCWMBUS: "MODULE_TYPE","RC1180-MBUS3,2.00,3.14".

• The module is switched into a mode in which it discards messages captured in the Compact Frame (CF) format and stores only messages received in the Full Frame format. 
  • 0 - disabled, all messages are stored.
  • 1 - enabled, CF are discarded.

at^scwmbus?

• The command displays the currently set interface values.

at^scwmbus=?

• The command displays the Wireless M–Bus setting options.