"Error: Cannot hold value outside clock edge" ?

Thanks for the replies.

Another error is when I compile

elsif (S_ReceiveParametersFromRS232='1' and RS232InInt'Event and RS232InInt='0' ) then

I get the errors :

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Error (10397): VHDL Event Expression error at ddfsControl.vhd(78): can't form clock edge from S'EVENT by combining it with an expression that depends on a signal besides S

Error (10658): VHDL Operator error at ddfsControl.vhd(78): failed to evaluate call to operator ""and""

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where apparently Quartus does not allow three signals 'and' together.

I will go through the coding style guidelines chapter. However, the real challenge lies in re-writing the code.