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RS232 Checksum calculation in level sequences

For calculating checksum in level sequences you will need to make a dynamic calculating string.

In the example below we will use the Philips protocol!

 

Always start by reading the protocol of the device thoroughly.
All good configuration starts this way!!!
In section 2.3 of the Philips RS232 protocol we see the structure for the messages we are about to construct for the Philips display.


Notice the way the Checksum is calculated, in this case it’s done with an XOR function.

 

Philips uses a protocol, where the ensure the integrity of the sent message by calculating the checksum!
The checksum is a mathematical calculation of all of the bytes prior to the checksum!

Each field is 1 Byte = 8 bits = 2 Hex digits

 

What do we need in order to calculate the checksum???

 

In this case we would like to change an input, therfore we have to do the following:

 

  • Find the right section in the protocol(Message Set)
  • Choose the input we want to set (HDMI 2)
  • Note the command and use the example in order to edit our command.

 

 

Rewrite the command so that it fits…

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Checksum

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The procedure is the same for LAN!

Please also find this description attached as PDF.

 

 

 

 

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