LZQJ-XC is an electric meter from the German manufacturer EMH, which is sold in Slovakia by the Schrack company. The attribute XC in the name means that, compared to the classic LZQJ, it has a slot for a plug-in module from the EMH Variomod XC or Interface Module XC model series. Plug-in modules add additional communication interfaces to the electricity meter.

 
Figure 10 - View of LZQJ-XC with and without bottom cover

Figure 11 - LZQJ-XC communication interfaces

In Figure 11, the main elements of the terminal block and communication interfaces are marked. They are also described on the label stuck on the inside of the lower cover.

    1. Terminal box for the electrical network. Only phase 1 and the ground are connected in the picture.
    2. Terminals 23, 24, 27 - RS485 interface integrated directly on the electricity meter.
    3. Plug-in module GPRS antenna connector. (In testing we used a piece of copper wire instead of the original antenna and it was sufficient.)
    4. RS485 interface terminal block on the plug-in module. Through this interface, it is possible to connect the RS485 bus with other electricity meters - the plug-in module then serves as an IP and serial communication translator.
    5. Optical interface - for attaching an optical head.


EMH-COM utility software

We had the EMH-COM utility software (license-restricted version of the EMH-COMBI-Master 2000 tool) available for the electric meter, which allows you to read values from the electric meter, set the exact time, and write the configuration prepared in a text file (with the extension *.set) to the electric meter, which someone had to create before in the COMBI-Master tool. It uses the IEC62056-21 protocol for communication and can connect to the electricity meter through all interfaces.
The connection configuration can be accessed via the menu Settings | Program Settings... can be used to select the type of communication on the General tab:

  • COM port – serial communication via optical head or RS485.
    • Select COM8 (or other appropriate port) and leave the Bluetooth OKK blank, even if communicating via a USB optical head
    • Baud rate:
      • The optical head uses Mode C
      • RS485 communicates at a speed of 4800 Bd.
  • TCP/IP – communication via the IP interface of the plug-in module
    • IP address – according to the IP address assigned to the device
    • Port number: 8000 – Variomod XC uses TCP port 8000 by default.

For most operations, it is also necessary to enter a password, which is set to "00000000" by default in the electricity meter. It is entered in both the Login-password and W5-password fields.
If the electricity meter is connected to a serial bus with several electricity meters, it is necessary to enter the serial number of the electricity meter in the field Meter - address. Otherwise, this data is optional.


Variomod Manager utility software

Variomod XC plug-ins are devices with their own configuration and their own configuration tool. They can be configured when plugged into the power meter. For initial initialization, it is best to use an optical head, later it is also possible to connect via TCP/IP directly via the plug-in module.
The following steps are required to establish a configuration connection:

  • In the main menu of the program: File | New
  • Choose the type of plug-in module from the dialog (XC Ethernet and XC GSM/GPRS were available for testing).
  • Enter the identification data of the plug-in module according to the nameplate on the module



Figure 12 - Specifying the Variomod XC type

  1. Use the connection button (marked with the letter A in the picture) and choose the type of connection:
    1. Direct – for RS485 on the plug-in module (Baud rate: 4800, Parameter: 7E1, Password: no password)
    2. Mode-X – for an optical head (Baud rate: 300, Bluetooth OKK: empty, Meter address: serial number of the electricity meter, Configuration password: empty)
    3. TCP/IP - remote communication (Company: empty, TCP/IP address: port: IP address of the device, port 8000, Configuration password: empty)
  2. Confirm OK, wait a while - establishing a connection takes up to 30 seconds.
  3. The dialog "File has been changed. Save?" appears – you can save the connection settings.
  4. The program downloads basic information from the plug-in module - it can then be configured.


APN setting for GPRS communication

  1. In the connected Variomod Manager, mark the GPRS item in the configuration tree.
  2. Press Read.
  3. The progress of reading the values will be displayed.
  4. Enter the correct APN (and possibly other parameters according to the operator's instructions).
  5. Write the configuration to the plugin.


Figure 13 APN setting to Variomod XC GPRS

It is possible to set the method of obtaining an IP address in Variomod XC Ethernet using an analogous procedure.

DLMS/COSEM protocol activation

In the basic setting, the electricity meter communicates only with the IEC62056-21 protocol on all its interfaces (optical, RS485, plug-in module interface). For activation, it is necessary to send the following SET of parameters via the EMH-COM program to the electricity meter. The SET must be stored in a file with the *.set extension and is sent with the File | Transfer... command
_pac000(0001000002000000)
_hcc002(0000)
_hcc012(FFFF)
_hpc020(00000000)
In the default setting, Variomod XC plug-in modules communicate with the electricity meter via the internal bus with serial communication parameters 4800Bd 7E1. It is necessary to switch parameters to 4800Bd 8N1 in Variomod Manager. The procedure is similar to that in chapter 2.3.3 - the elements in the image marked as Parity must remain empty.

Parameters for DLMS communication

The electricity meter uses the HDLC protocol on the relational layer. The electricity meter requires the use of a physical device address. The addresses are:

  • HDLC physical device address - 256 is added to the bottom 4 digits of the serial number
  • HDLC logical device address – 1
  • HDLC client address – 16 (0x10) for unauthorized access without a password, 32 (0x20) with a password
  • Password = 00000000


Other observations

From the testing experience, it can be concluded that the DLMS protocol was added to LZQJ-XC only later, and IEC62056-21 clearly prevails. This can be seen, for example, from the fact that if a problem occurs during the establishment of DLMS communication, the electricity meter switches to IEC21 mode and starts "Readout" - the output of values to all communication channels.
If the LZQJ-XC is currently performing a "Readout", it cannot be interrupted other than by disconnecting the power supply. If someone tries to communicate with it at that time, instead of a response, it will only receive a "piece" of the readout that just came from the electricity meter.
LZQJ-XC knows several "Readout" lists. The classic one, described in the IEC62056-21 standard, is called T1. In addition, it also knows T2, T3, and TS. Attention, T2 contains a very long list of Load profile values, it can take up to 10 minutes until he finishes this list.
The IEC62056-21 standard explicitly states that the slash character "/" is a formatting character that cannot be used in a data block as part of data. However, EMH also uses it in data to indicate "P/S" units.
The Variomod XC plug-in cannot handle two independent TCP connections at the same time. However, through one TCP connection, it is possible to have parallel open DLMS sessions with several electricity meters on a shared serial bus.



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