STL bit and byte numbers

I'm very weak in STL, I got the code snippet from the internet, so I don't know exactly what it does?

Manglemender said:

Also, the two AND statements prior to the Transfer instruction have no effect on the Transfer so they serve no purpose. What was the intent for those instructions?

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Avatar_41 said:

What I don't understand is: Why can't I see these 0.0 or 0.1 values, so what can I do to see 0.0 instead of -2130706432?

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Whe you monitor the FC, the Siemens monitoring software converts the value in AR1 to a string so it shows, for example, I0.1


If you want to see that on the output of your FC you will have to use a string type and write the code to convert the value in AR1 to a string.

#byte_number and #bit_number are variables passed into the FC via the HMI.

Make sure to include code to ensure the input byte and bit number are within valid limits or it will cause the CPU to fault.

Avatar_41 said:

I'm very weak in STL, I got the code snippet from the internet, so I don't know exactly what it does?

Click to expand...

I suspect that in your oginal code snippet the the last statement was = #Output (boolean) rather than T #Output. The two preceeding AND statements set the state of the binary result bit (BR) in the Condition Code Register (CCR) and this then governs the status of the output.

While monitoring FC2 you see the I11.7 in the Address register (AR1). The T #Output statement moves the contents of Accumulator1 (Standard) to the output. What you see is the numeric representation of the address as a signed DINT

Nick