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GOOSE: Why display floating-point in hex?

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Feature request:

When displaying the data of a GOOSE packet, could you please display the value of the floating number to the right of the hex value? I have to admit I am a little slow to convert in my head so I can see that 0840600000 is f3.5 :=)

Thanks

asked 13 Feb '13, 09:05

ecs1749's gravatar image

ecs1749
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edited 13 Feb '13, 10:07

helloworld's gravatar image

helloworld
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One Answer:

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answered 13 Feb '13, 09:12

Jim%20Aragon's gravatar image

Jim Aragon
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accept rate: 24%

I guess it's this defenition in the Goose asn1 specification. FloatingPoint ::= OCTET STRING as it's defined as OCTET STRING it will be displayed in hex. 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.

(13 Feb '13, 11:37) Anders ♦

Which .cnf file? I am pretty new to GOOSE & Wireshark in general. What I am seeing when I look at the goosePdu -> allData, it displays something like Data: floating-point (7) and then "floating-point: 0840900000". Now, it's obvious to me Wireshark knows it's a float and that the value is 4090 0000. Why can it just say: "floating-point: 0840900000 (+4.500000e+00)"?

(15 Feb '13, 09:47) ecs1749

The GOOSE dissector in Wireshark is auto-generated from an asn1 definition of the protocol. As @Anders says, in that definition it defines FloatingPoint types as an unlimited length string of bytes.

The .cnf file allows "overrides" of the definition but as it appears to be of unlimited length it might not be correct to just do that.

Someone with access to the (not free) protocol spec (IEC61850-x-x) should check the latest definition of the type.

Note there there also seems to be issues on this type: http://tissues.iec61850.com/tissue.mspx?issueid=817

(16 Feb '13, 00:09) grahamb ♦