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4.2.5 Types of RCS Classes
e OVERVIEW-ML
r MULTIMEDIA-TERMINAL MMT-X, MMT-NT, EOS
s MULTIMEDIA-TERMINAL MMT-S
m AVC-BOX, DIGITAL SWITCHBOX, ANALOG INPUT BOX, HERMES D2D,
HERMES V2A, HERMES DXD, HERMES VXA
Table 4-4
4.3 How to calculate the checksum
The checksum is being evaluated from the recipient to make sure that the message received has not been
corrupted. The checksum is a kind of sum over all fields from <TYPE> to <Body> or <TYPE> to
<STATL> respectively (Acknowledge).
The checksum is calculated by transforming each character of the message into its ASCII code. The
ASCII values are added, and this sum is converted into a hex number. The checksum uses the last two
digits of this hex number. If the hex number consists of non-numeric characters, these characters have
to be lower case characters.
Example:
Let's consider the addressing procedure. The command for the addressing procedure is
A.
m00Axx
xx is the checksum to be calculated. The <TYPE> of the message is m, the <Body> 00A
message m 0 0 A
ASCII code 109 48 48 65
Summing up 270
converting into a hex number =10EH
<CHKL>
character has to be lower case!
e
<CHKH>
0
The correct addressing message :
m00A0e