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hello all of my friend.
i want to have a clear view of reading meters data procedure.
i read a lot of pages about this but if anybody know dlms cosem protocol well, plese help me.
assume that i want to read active energy from my power meter.
first of all i have to ask which type of client address do i have to use? public client is true?
then i have to know server address. server address consist of 2 part: physical and logical device address. when i want to read active energy, what do i have to use for server address?
we have a lot of obis codes in standard, where do we have to use obis codes? as i know obis codes are objects address, and for example active energy is an object with obis code :1.1.0.3.0.255
if i said wrong plese correct me.
aybody can explain a full procedure to read an object for example active energy from meter?
thanks mr. mikko for your good website
DLMS protocol
Hi,
Before you can read data from your device you must know following:
-Is device using Logical Name or Short Name referencing. Logical name is OBIS code.
If you know OBIS Code and device is using Logican Name, you can basically read directly.
If device is using Short Name, it's like address (Example: 0x540), you must first get Association View. Association View returns all Interfaces that device supports. After you have all Interfaces, you can search wanted OBIS code and read it using Short Name (Address).
-HDLC Client and Server addresses (Known also as Primary Station ID And Secondary Station ID)
Basically this should be standard, but there are manufacturers that do not work like this. Client address' size is one byte and it's value should be 0x10 when used as a public client.
Server's address consist from two parts: Physical Device and Logical Device.
I have explained it more detailed here: http://www.gurux.fi/node/336
If you have direct connection to the meter, you usually can use Client address 0x10 and server Address 1. If you have multidrop system, server address calculation can be based almost anything.
Example Landis+Gyr uses following way to count Server Address in multidrop systems. Take four last digit from Serial Number and add 1000.
Basically OBIS code values should be standard. Example 0.0.1.0.0.255 Should be "Clock object, first instance". OBIS codes are used so we know where to find Clock even if we change meter's type or manufacturer.
Compleate list of OBIS Codes is available here: http://www.dlms.com/members/OBIS%20list%20v2.3_GK051026.xls
- Reading data.
Set is Logical Name used.
Set Client ID (Address)
Set Server ID(Address)
Send SNRM and receive UA messages. Basically we are asking here how many bytes we can send in one packet.
Send AARQ and AARE messages. Basically here we tell what Logical Name referencing we want to use and client authentication information. (Client ID and password).
Now we are ready to read. We send read request to the meter that we like to read example active energy. Now active energy data size might be so big that it do not fix to one packet. for this reason meter returns data in several packets and every time when we receive one packet we must send ACK message to the meter before meter sends next one.
Hope this helps,
Mikko
thanks mr. mikko for your
thanks mr. mikko for your good help.
in obis list that dlms ua released, there are too many obis codes, i want to say that for example in a power meter we have about 10 parameters such as active and reactive enrgy, power factor and.... so what are the other obis codes for?
when i searched in xls file from dlms ua, i found a lot of obis codes that show active energy! how can i find the obis code of my desired parameter?
OBIS Codes
Hi,
Extra OBIS codes are reserved for future use and there are meters, like Landis+Gyr wich have several hundreds of OBIS codes in use.
Basic idea is that every meter SHOULD be use same OBIS codes. So even meter's manufacturer or model changes needed information is always found using same Logical Name. Like Clock 0.0.1.0.0.255.
You can ask from the device what OBIS codes it can offer.
You can read so called Association View and ask from device supported OBIS codes.
BR,
Mikko