Float values in GOOSE Protocol

Question

Hello,

I am working a product which supports IEC-61850 GOOSE protocol. I am using Wireshark for Packet analysis.

According to similar question on forum: here http://ask.wireshark.org/questions/18597/goose-why-display-floating-point-in-hex

I found that, Wireshark displays Float values as Hex becuase, " FloatingPoint ::= OCTET STRING as it's defined as OCTET STRING it will be displayed in hex.". The authour has suggested to "One could pssibly redifine the field in the .cnf file to FT_FLOAT but as there is no size constraint the OCTET STRING can be of arbitarry length.".

I tried to figure how can I display Float value as floating value instread of HEX, but I could not find the solution for this. Please helm me.

Best Regards, Dhaval

Answer 1

If this is true: http://tissues.iec61850.com/tissue.mspx?issueid=817 Final Proposal: Change Table A.2: Encoding allData in Fixed-length GOOSE Message. Basic Data Type Float 32 ASN.1 Tag 0x87 ASN.1 Len = 5 Comment: MMS Data Production: first byte=8, remaining 4 bytes represents the floating point number in IEEE 754 single precision format.

Add someting like this to the .cnf file

#.FN_BODY FloatingPoint VAL_PTR= &parameter_tvb
tvbuff_t    *parameter_tvb;
int length;
%(DEFAULT_BODY)s
if (!parameter_tvb)
return offset;
length = tvb_length(parameter_tvb);
if(length!=5)
return offset;
if(tvb_get_guint8(parameter_tvb,0) != 8)
return offset;
proto_tree_add_item(tree, hf_goose_foo, parameter_tvb, 1, 4, ENC_BIG_ENDIAN);

and add the hf_ variable to the template file with FT_FLOAT or something along those lines. run make goose in the asn1 folder and then recompile Wireshark.