Siemens Encode & Decode function

TEOWK

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• Nov 7, 2004

• #1

I am studying Siemens s7-300 PLC. There are 2 built-in function that seems confusing to me. ie. Encode & Decode FC83
Please suggest an application example using this function.

 

jacekd

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• Nov 8, 2004

• #2

In which library did you find it ? Number only is not enough.

 

TEOWK

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• Nov 8, 2004

• #3

it's under Standard Library....TI-S7 Converting Blocks
oh... and i made a mistake
it should be FC96 and FC97
sorry for the mistake

 

Last edited: Nov 8, 2004

jacekd

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• Nov 8, 2004

• #4

OK. Now I see. So it looks to me like enocode makes convertion from 1 of 31 code into binary and decode makes opposit convertion.
Possible app is keyboard (it can give you number of pressed button) for encode FC or (not sure about my translation into English) "light dial/scale" for decode FC.

 

jvdcande

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• Nov 8, 2004

• #5

To find out what a certain function does, it is enough to select that function in the instruction browser and press the F1-key.

The funcions you're talking about are:

1. FC96 - ENCO
   This function returns in RET_VAL the bitnumber of the first set bit in the value in parameter IN starting from the right.
   IN = 0001_0101_0000_1000_0101_1111_0100_0000 -> RET_VAL = 6
2. FC97 - DECO
   This functions sets one bit (bitnumber 0-31 in parameter IN) in a double word (parameter RET_VAL). If the value in IN is greater than 31, modulo 32 is calculated first, eg. 35 sets bit 3.
   IN = 5 -> RET_VAL = 0000_0000_0000_0000_0000_0000_0010_0000
   [/list=1]
   Kind regards,