Serial Number Data Type

By technoshell, 5 June, 2025
Forums
Gurux.DLMS

Good Morning Sir,

I am using Arduino client code on ESP32 to read meter in MR mode with LLS. I am able to read the Manufacturer name and Active Energy successfully. But when I read Serial Number with obis code 0.0.96.1.0.255 I get the ASCII string on HPL meter but a Octet String on Secure Meter.
I use the code as under
cosem_init(BASE(ldn), DLMS_OBJECT_TYPE_DATA, "0.0.96.1.0.255"); // OBis for Serial No
com_read(BASE(ldn),2); // Read
obj_toString(BASE(ldn), &data);

How to identify what type of data is received octet string or normal string. ?Accordingly we can call for respective translation code.

Thank You and Best Regards
Technoshell

Kurumi

9 months 1 week ago

Hi,

You can check the variant type like this:

if (ldn.value.vt == DLMS_DATA_TYPE_OCTET_STRING){
...
}
else if (ldn.value.vt == DLMS_DATA_TYPE_STRING){
...
}

BR,
Mikko

technoshell

9 months 1 week ago

I think it was Hex coded. It showed up when I put in on Hex to ASCII converter. I will check sir. Thank you so much for your help.

technoshell

9 months 1 week ago

Sir ,
ldn.vt throws error. Intellisense shows ldn has only two attributes one is base and other is value. Please advise.

Bet Regards

Kurumi

9 months 1 week ago

Hi,

My bad. The value is missing from the example code. I updated the code.

BR,
Mikko

technoshell

9 months ago

Thank You Sir.
I wanted to read the serial number so I used the code

int com_readNamePlateSrno()
{
unsigned char i;
int ret;
char* data = NULL;
gxData ldn;
//Initialize connection.
ret = com_initializeConnection();
if (ret != DLMS_ERROR_CODE_OK)
{
GXTRACE_INT(PSTR("F"), ret);
return ret;
}

cosem_init(BASE(ldn), DLMS_OBJECT_TYPE_DATA, "0.0.96.1.0.255"); // OBis for Serial No
com_read(BASE(ldn),2); // Read

obj_toString(BASE(ldn), &data);

Serial2.print(data);

obj_clear(BASE(ldn));

free(data);

}

The result shows
Index: 2 Value: 54308521<CR><LF>

The Serial number is correctly read as 54308521
But soon after printing the above the program hangs and prints continues garbage.

Is there something wrong I am doing?

Thanks and Regards

Kurumi

9 months ago

Hi,

You need to close the connection after you have read the data. Now you leave it open and I believe that next com_initializeConnection is failing.

It's also important that you check that com_read is successful. The reading might sometimes fail.

BR,
Mikko

technoshell

9 months ago

Thank you sir. This worked well on the old version of Arduino code. I then downloaded the latest version to work with Encryption and facing some issues. But I will create a separate topic for this. Thanks once again