step 5 programming instructions discussion

Hi Zizo soliman

To understand this logic, you need to first understand the Analog Input value representation in S5.

I have attached an extract from S5-100U manual for your reference.

Here is an Explanation of the statement :

L PW 172   // Read Analog Input PW 172

SSW 3  //  Shift the Word with Sign 3 Bits to Right ( Discard the Overflow, Error and Irrelevant Bits )

ADD KF -512 // Subtract the offset for 4 mA ( for 4-20mA Value at 4mA = 512 ) to get 0-2048 at 4-20mA

L KF +333

XF             // Multiply with 333  

JP M001  // Jump to M001 if calculated Value is +ve

L KF 0    // Else Substitute with Zero ( Ignore -ve Values )

M001   // Label

SSD 11  // Shift Accumulator ( As 32 bit ) 11 bits to the Right while retaining sign ( Divide by 2048 ) 

T DW 11 // Transfer to DW 11

Effectively you will have 4-20mA Scaled as 0-333

Hope this helps

Cheers

Navnag