NP73E is an electricity meter from the Moldavian manufacturer Addax, which is sold in Slovakia by Transtech. Several models are included under the designation NP73E (during testing, NP73E.2-... with direct consumption measurement and NP73E.3-... with semi-direct consumption measurement were available). A plug-in module is attached under the lower cover of the electricity meter, connected via miniUSB to the electricity meter, thus adding additional communication interfaces.

Obrázok 7 Pohľad na NP73E a zásuvný modul pod spodným krytom

Figure 8 - NP73E communication interfaces

In Figure 8, the main elements of the terminal block and communication interfaces are marked:

1. 1. Terminal box for the electrical network. Only phase 1 and ground are connected in the picture.
   2. MiniUSB connector that connects the plug-in module to the electricity meter.
   3. RS485 serial interface.
   4. Optical interface - for attaching an optical head.

Utility software CosemClient

CosemClient utility software was supplied with the NP73E power meter, which can be used to read the values of all COSEM objects from the power meter as well as to change the configuration of the power meter. CosemClient uses the Sentinel hardware token, without which the software can be used in read-only mode.

Figure 9 - Sentinel with license for CosemClient
The basic configuration scenario is described in detail in the document \\srvcomp1\DEV_Support\COMMUNICATIONS\IEC 62056\ADDAX-Transtec Presov\Communication via optohead or GPRS v2.pdf.

Parameters for DLMS communication

The communication with the electricity meter via IP uses IEC62056-47 on the relational layer, via RS485 it uses HDCL. The following addresses are used:

• HDLC physical address = cannot be clearly derived, it is defined in the electricity meter settings. However, the electricity meter responds to HDLC broadcast, which is used in the CosemClient application.
• HDLC logical address = 0x01
• HDLC client address = 16 (0x10) for unauthorized access without password, 1 (0x01) with password
• password = transtec (Note: electricity meters delivered directly from Moldova may also have the password set to 00000001 or 00000002).

Other observations

This electricity meter uses DLMS with logical name addressing of COSEM objects. According to the standard, it must and also contains a COSEM object of type AssociationLN (class Id = 15) with the logical name 0.0.40.0.1.255, but the object does not contain any values, and according to the manufacturer, "the object is not implemented". However, the list of all COSEM objects in the device is in documentation \\srvcomp1\DEV_Support\KOMUNIKACIE\IEC 62056\ADDAX-Transtec Presov\ZSE_and_SSE_Project._Object_Model._Rev.1.4.doc.
The optical interface is active only shortly after the start of the electricity meter. Later, it can be activated by holding the button on the main panel for 6 seconds, or by pressing, then holding, and then pressing again. The active optical interface signals the electricity meter by simultaneously displaying the signs  and . When the optical interface is active, the others are inactive.
Holding down the button on the front panel for too long (more than 10 seconds) will trigger the action "subscriber disconnection" or, if it is disconnected, "subscriber connection".