MMS报文分析示例（三）

Variable Management

 

 

1.  Read request

 

MMSPdu Received ::=

A0 1E 02 01 0A A4 19 A1  17 A0 15 30 13 A0 11 80 0F 66 65 65 64 65 72 31  5F 33 5F 70 68 61 73 65

 

[0]  A0 1E  --  ConfirmedRequestPDU

{

02 01 0A  --  invokeID

 

[4] A4 19  --  ConfirmedServiceRequest, A4 = Read

{            

 

[1] A1 17  --  variableAccessSpecification

{               

 

[0] 30 13  --  listOfVariable

(30 = 00 1 10000, Universal Constructed)

{

 

[0] A0 11  --  variableSpecification

{

[0] 80 0F 66 65 65 64 65 72 31 5f 33 5f 70 68 61 73 65  --  name

}

}

}

}

}

 

 

where,

invokeID::=0A

Identifier (name of variable to read)::="feeder1_3_phase"

 

 

2.  Read response

 

Assume

 

typedef struct var_def

{

int a;

int b;

} VAR_DEF;

 

VAR_DEF feeder1_3_phase;

 

MMS Data Production

 

Data ::= CHOICE

{

[1] IMPLICIT SEQUENCE OF,-- arrayed data

[2] IMPLICIT SEQUENCE OF,-- structured data

[3] IMPLICIT BOOLEAN,

[4] IMPLICIT  BIT STRING,

[5] IMPLICIT INTEGER,-- signed int

[6] IMPLICIT INTEGER,-- unsigned int

[7] IMPLICIT Floating Point,

[9] IMPLICIT OCTET STRING,

[10] IMPLICIT VisibleString,

[11] IMPLICIT GeneralizedTime,

[12] IMPLICIT TimeofDay,

[13] IMPLICIT INTEGER,-- BCD

[14] IMPLICIT BIT STRING,-- boolean array

[15] IMPLICIT OBJECT IDENTIFIER

}

 

The encoded structure of the encoded data can be determined via VAR_DEF

 

VAR_DEF::=          TAG       

------------------------------------------- 

struct {                 A2

inta;              85

intb;              85

}

 

 

MMSPdu Received ::=

A1 0F 02 01 0A A4 0A A1  08 A2 06 85 01 00 85 0100

 

[1] A1 0F  --  ConfirmedResponsePDU

{

02 01 0A  --  invokeID

[4] A4 0A  --  ConfirmedServiceResponse, A4 = Read

{

 

[1] OF A1 08  --  listOfAccessResult

{              

A2 06  --  success, Data of struct

{          

 

85 01 00  --  int a;

85 01 00  --  int b;

}

}

}

}

 

where,

invokeID::=0A

value of a::=00, value of b::=00