Hello everyone,

I have problem when I change remotely the Time Zone of Astronomical Clock. If the value is positive or zero everything is working fine but when it is negative nothing changes.

I have tried to change it bit by bit. I have tried to change the sequence of bytes. I have followed the instructions descripted on the following link https://support.industry.siemens.com/cs/mdm/100782807?c=85315142923&lc=en-US. I have tried via TIA Portal v16. I have tried via node-red. The result is always the same.

When I change the variable via the function block settings in the LOGO!SoftComfort, TIA Portal and node-red return the following:

Reading Low Byte

If value is positive (+) -> Low Byte = "00000000"

If value is zero (0) -> Low Byte = "00000000"

If value is negative (-) -> Low Byte = "11111111"

Reading High Byte

If value is positive (+2) -> Low Byte = "00000010"

If value is positive (+1) -> Low Byte = "00000001"

If value is zero (0) -> Low Byte = "00000000"

If value is negative (-1) -> Low Byte = "11111111"

If value is negative (-2) -> Low Byte = "11111110"

Reading Whole Word

If value is positive (+2) -> Word = "16#0002"  & Int = "2"

If value is positive (+1) -> Word = "16#0001" & Int = "1"

If value is zero (0) -> Word = "16#0000" & Int = "0"

If value is negative (-1) -> Word = "16#FFFF" & Int = "-1"

If value is negative (-2) -> Word = "16#FFFE" & Int = "-2"

Everything seems logical when reading. Everything is working fine when writing positive numbers or zero but I can't find a solution to write negative values to this parameter.

Regards

Nek

Hello ixo65,

thank you for your response.

I saw a big difference when the value is negative.

If the value is (+6): we have the same result.

If the value is (-6): your result is "2#1000_0000_0000_0110" but mine is "1111_1111_1111_1010".

Both bytes are completely different when the value is negative.

My version of LOGO! Soft Comfort is v8.3.0 and the hardware is V1.08.01. I can't tell that there is an issue because every other parameter works fine.

I have tried to write each byte separately but without success.

Every other parameter of any function block I have used, works with no problem. 

I have wasted so many hours on this issue and I think that this is a bug.

This is from a simulation. Am I right?

When I am on simulation I have the same results.

But when I am online and I want to exchange data with other devices, the results are different.

I have no problem to read/write any other parameter with the same format and characteristics.

The only thing I can't do, is to write negative values on Time Zone parameter.

At least we agree that it is a software bug.

Thank you very much for your time.

ixo65

I kept brooding and brooding ...

Since Siemens likes to stick to old braids (also when it comes to LOGO!), I now suspect that it is a signed 3-digit BCD number.

I have checked earlier on .. it is not BCD.
I have used GMT -10 and the answer came as 16#800A.
-- strange.