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Paradyne DMD15L Source ID, Destination ID, Frame Sequence Number, Opcode, Checksum

Models: DMD15 DMD15L

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DMD15/DMD15L IBS/IDR Satellite Modem

User Interfaces

 

 

<SOURCE ID>:

The Source Identifier defines the multi-drop address

 

 

origin.

 

 

 

 

Note: All nodes on a given control bus have a unique

 

 

address that must be defined.

<DESTINATION ID>:

The Destination Identifier serves as a pointer to the

 

 

multi-drop destination device that indicates where the

 

 

message is to be sent.

 

 

<FRAME SEQUENCE NUMBER>:

The Frame Sequence Number (FSN) is a tag with a

 

 

value from O through 255 that is sent with each

 

 

message. It assures sequential information framing and

 

 

correct equipment acknowledgment and data transfers.

<OPCODE>:

The Operation Code field contains a number that

 

 

identifies the message type associated with the data that

 

 

follows it. Equipment under MCS control recognizes this

 

 

byte via firmware identification and subsequently steers

 

 

the DATA accordingly to perform a specific function or

 

 

series of functions. Acknowledgment and error codes are

 

 

returned in this field. 1 Byte for the DMD5000 protocol,

 

 

and 2 Bytes for the DMD15 protocol.

<DATA >:

The Data field contains the binary, bi-directional data

 

 

bytes associated with the <OPCODE>. The number of

 

 

data bytes in this field is indicated by the <BYTE

 

 

COUNT> value.

 

 

<CHECKSUM>:

The checksum is the modulo 256 sum of all preceding

 

 

message bytes, excluding the <SYNC> character. The

 

 

checksum determines the presence or absence of errors

 

 

within the message. In a message block with the

 

 

following parameters, the checksum is computed as

 

 

shown in Table 4-7.

 

 

 

 

 

 

 

 

Table 4-7. Checksum Calculation Example

 

 

 

 

 

 

 

 

BYTE FIELD

DATA CONTENT

 

RUNNING CHECKSUM

 

 

 

 

 

 

 

 

<BYTE COUNT> (Byte 1)

00h = 00000000b

 

00000000b

 

 

 

 

 

 

 

 

<BYTE COUNT> (Byte 2)

02h = 00000010b

 

00000010b

 

 

 

 

 

 

 

 

<SOURCEID>

F0h = 11110000b

 

11110010b

 

 

 

 

 

 

 

 

<DESTINATION ID>

2Ah = 00101010b

 

00011100b

 

 

 

 

 

 

 

 

<FSN>

09h = 00001001b

 

00100101b

 

 

 

 

 

 

 

 

<OPCODE> (Byte 1)

00h = 00000000b

 

00100101b

 

 

 

 

 

 

 

 

<OPCODE> (Byte 2)

03h = 00000011b

 

00101000b

 

 

 

 

 

 

 

 

<DATA> (Byte 1)

DFh = 11011111b

 

00000111b

 

 

 

 

 

 

 

 

<DATA> (Byte 2)

FEh = 11111110b

 

00000101b

 

 

 

 

 

 

 

TM051 - Rev. 5.8

4-45

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Paradyne DMD15L operation manual Source ID, Destination ID, Frame Sequence Number, Opcode, Checksum
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