Error when transferring larger and segmented block for ImageTransfer class.

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By icabrera , 27 February, 2019
Forums
DLMSDirector

Hello,

I am implementing the ImageTransfer ( IC = 18 ) into a smart meter.

The problem I found in Gurux DLMS Director is with the codification of image_block_transfer method when the image_block_size does not fit into a single HDLC frame.

When using a larger block, i.e. 128 bytes, HDLC segmentation is ON and then the transmitted packet by Gurux is incorrect.

Consider the following packet:

7E A8 8C 00 02 58 7D 09 BA 72 70 E6 E6 00 C3 01 C1 00 12 00 00 2C 00 00 FF 02 01 00 00 00 00 01 6D 02 02 06 00 00 00 00 09 81 80 01 00 00 00 00 01 00 00 01 00 00 00 09 00 00 00 0A 00 00 00 88 91 03 00 49 55 53 41 2D 41 4D 49 2D 30 2E 30 2E 37 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 6F 72 69 67 69 6E 2F 6D 61 73 74 65 72 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 33 37 36 63 31 64 61 00 D4 AD 7E

The problem are following bytes: (00 00 00 00 01 6D) found between Class ID, OBIS, Method, Parameters (00 12 00 00 2C 00 00 FF 02 01) and ASN1 codified data (02 02 06 00 00 00 00 .... ).

When using a small block, i.e. 64 bytes. HDLC segmentation is OFF and then, the transmitted packet by Gurux is correct.

7E A0 65 00 02 58 7D 09 98 7F 3C E6 E6 00 C3 01 C1 00 12 00 00 2C 00 00 FF 02 01 02 02 06 00 00 00 00 09 40 01 00 00 00 00 01 00 00 01 00 00 00 09 00 00 00 0A 00 00 00 88 91 03 00 49 55 53 41 2D 41 4D 49 2D 30 2E 30 2E 37 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 6F 72 69 67 69 6E 2F 6D DE C1 7E

Between Class ID, OBIS, Method ID, Parameters and ASN1 codified data there are no additional bytes.

I don't know if this problem is related with the HDLC segmentation or not because the additional (and erroneous) bytes are at the beginning of the packet and not in the boundaries of segmented packets.

Best Regards,

Ivan Cabrera