Reading counter data with the IEC 62056-21 protocol

[Authorless]

I need to read the energy delivered (total Kw) from two ISKRA MT831 three-phase energy meters.

The meters have the RS485 serial interface with the IEC 62056-21 mode C protocol with or without password, I need to read the energy value to manage a report of the same on a printout.

It is possible to manage this reading from systems SlimLine ?

[Sergio Bertana]

The IEC 61107 or IEC 62056-21 standard is an international standard that describes a protocol that allows a computer to read data from electricity, water and gas tariff meters.

The protocol includes a phase of Sign-On with the counter, during this phase it is necessary to provide an access code (in the case of ISKRA meters this is the serial number of the meter), and the counter provides a password that can be used to encrypt the data.

Once the Sign-On has been completed, it is possible to request the value of its registers from the meter using the identification codes OBIS to 5 characters (IEC 62056-61).

For the family SlimLine we have developed a special function block that automates all operations, it is necessary to pass the serial number of the meter and the OBIS code of the register to be read. The function block performs the Sign-On on the counter and returns the value of the indicated register (See Documentation).

[Sergio Bertana]

I add the links to some manufacturers of optical couplers that can be used as an interface between the serial port of the SlimLine and the counter.
 
For example the Zvei probe of TeamWare, of which I enclose datasheet.
Or the model ProMATIC RC4-IR Probe, of which I also attach the datasheet.
 
But every manufacturer of meters has a model of probe in their catalog for reading the values.

[Raffaele]

I am interested in the possibility of implementing the IEC 62056-21 protocol. I would need the following information:

1) The IEC 62056-21 protocol from reading the data sheet is an option I would like to know about any additional cost.
2) Is it possible to query more devices (2 meters in the case of our interest) on the same bus?
3) Having the need to use 2 RS485 buses, is it possible to use an RS232 port + RS232 / RS485 converter to support the second Bus?

In practice I would like to use the Slim Line controller as IEC62056-21 / Modbus RTU protocol converter.

In the previous posts we refer to the use of an optical converter: is it possible to directly use the RS485 communication port (IEC 62056-21) possibly available on the energy meter terminal board?

[Sergio Bertana]

1) Yes, theIEC 62056-21 protocol management FB it is sold with an additional cost.
2) Yes, to access each device (Counter) it is necessary to provide a code that corresponds to the serial number of the meter itself, therefore, once the access request has been authenticated by means of the serial number, only that meter can be accessed via the bus.
3) Yes, it is possible to connect to the RS232 serial ports of the SlimLine an RS232 to RS485 converter (see ATC-105 o ATC-108) to have more ports in RS485.
It is possible to create an IEC62056-21 / Modbus RTU protocol converter, just connect the IEC62056-21 bus on one port and on the other it will be possible to have the Modbus RTU protocol both slave (Native in the operating system) and Master through a special FB . The optical converter is a possibility for meters that do not have the RS485 interface, but if the meter already has the RS485 interface it is much easier to connect it directly.

[Sergio Bertana]

It is available for download from the page SlimLine, a demonstration program (Ptp122a000) that reads 3 different registers from an electricity meter.

Using this demonstration you can easily modify it to suit your needs.

Note! Even if the demonstration uses a protected function block, you can test its operation for 30 minutes, then the function block freezes and you need to restart the system.

[Angelo]

I tried to use the FB with an Itron SL7000 meter via 485 (customer port of the meter) without success. Has it already been tested with this type of counter and / or are there special settings to set?

[Sergio Bertana]

We developed the FB for a large customer with Iskra meters, we then experienced that with other meters there were more or less large differences.

It is not our core business to develop applications, the work has been carried out by a customer of ours who has adapted the FB by developing its own port on by now I believe almost all the meters on the market.

For serial applications we can evaluate a modification of the FB to adapt it to different meters, you can contact our sales office for agreements.

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