IEC101

IEC 870-5-101 frame with variable length
2015-04-13 15:40:12.189 Gateway.Imatra.port.write - 68 16 16 68 53 01 00 24 01 03 01 00 1B 04 3C A2 C2 40 00 AB 28 28 0F 0D 04 0F A6 16

24 01 03 01 00 1B 04 3C A2 C2 40 00 AB 28 28 0F 0D 04 0F A6 16

16	end
A6	checksum
AB 28 28 0F 0D 04 0F	Timetag http://phobos.martem.ee/shr/CP56t2a/CP56Time2a_experimental.exe
00	Quality descriptor (iv, nt, ..., defined in 7.2.6.3)
3C A2 C2 40	Value (0x40C2A23c == 6.082304) defined in 7.2.5) http://gregstoll.dyndns.org/~gregstoll/floattohex/
1B 04	IOA (object address 2 bytes)
01 00	Common addr of ASDU (defined in 7.2.4)
03	Cause of transmission COT (1 byte) defined in 7.2.3)
01	Variable structure qualifier (nr of objects)
24	Type identification (type 36 short float with timetag)

68 16 16 68 53 01 00

01 00	Link address (2 bytes)
53	Control field	(PRM, FCB, FCV, DFC, ACD, Fuction codes) (defined in 5.1.2 -> 870-5-2)
68	Start
16	Length(=22 dec)
16	Length
68	Start

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EXAMPLE: Measured value, short floating point value with time tag CP56Time2a M_ME_TF_1

68 40 40 68 73 01 00
	24 04 03 01 00
		38 11 00 00 00 00 00 D9 5C 28 0F 0D 04 0F	addr 472 value 0 time 2015.4.13 15:40:23:769
		8D 02 48 30 70 43 00 D9 5C 28 0F 0D 04 0F	addr 653 value 240,188 time 2015.4.13 15:40:23:769
		8E 02 00 00 00 00 00 D9 5C 28 0F 0D 04 0F
		8F 02 00 00 00 00 00 D9 5C 28 0F 0D 04 0F
C9 16