Справочник Пользователя для Siemens 505-2557

Advanced Function Programming

In advanced mode the selection of degrees C or F is controlled by the
information stored and transferred to the module at WY72. The default
parameters are all zeroes which will cause the SIMATIC 505–2557 module
to return the value in degrees Centigrade x10. To select degrees F for the
module write a value of FFFF Hex to WY72 and use the documented
transfer procedure setting the data identification bits Y17, Y18 and Y19 to
1, 0, 0, (Refer to section 3.7).

To verify the Fahrenheit/Centigrade settings, the module reports back its
F/C status in WX57. The least significant bit (LSB) of WX57, corresponds to
channel one, while the most significant bit (MSB) corresponds to channel
16. A status bit of “1” indicates the channel is reporting in degrees F.
A status bit of “0” indicates the channel is reporting in degrees C.

All numbers used for scaling are expressed as signed

integers.

The numerical range for scaling is 

±

 32767. If a value of –32768 is loaded

into the module, then the value will be adjusted in the module to –32767.

Scaling operations may result in arithmetic

overflow. Errors of this kind for each channel may be detected with the
WX54 arithmetic overflow bits.

Overflow conditions can occur during normalization of the input value. If
the input word reaches  + 32767 or –32767 before the ADC (analog-to-digital
converter) saturates, then an overrange condition occurs and the overrange
bit for that channel is set.

In a scaling operation, if the result of scaling forces the value to the PLC to
exceed 32767, the overrange bit for that channel is set.

During an overflow condition, the value to the controller defaults to 

±

 32767

and there is no rollover of data. That is, the data does not return to zero and
beyond.

All numbers used for alarm setpoints are expressed as

signed integers. The numerical range for scaling is 

±

32767. If a value of

–32768 is loaded into the module, then the value in the module is adjusted
to –32767.