NAiS FP Series, Техническое руководство

Страница: 26 / 37

FP0 RTD Unit
I/O Allocation and Sample Programs
5.3 Programming with FPWIN GR
5.3.1 RTD Types Pt100, Pt1000, Ni1000
Ladder program to read data from input channels
This program shows you how to store temperature data for CH0 to CH5 of the FP0 RTD unit
installed as expansion unit no.1 in data registers DT0 to DT5.
EXAMPLE
REFERENCE
For further information, see page 14, I/O Allocation and Sample Programs.
Conversion data switch flag
When transferring the data from the FP0 RTD unit to the control unit, it is converted to 32-bit
data including the channel information. Data for WX2 can be used as is, but the following
procedure is required for WX3 data since its higher 2 bits are used as a conversion data
switch flag.
PROCEDURE
1. When temperature data is negative, the data is automatically represented as
two's complement of WX2 and WX3: bit F of WX2 and bit D of WX3 will be
“1”.
2. The higher 2 bits of WX3 are used as conversion data switch flag. After
saving the channel information, the conversion data switch flag needs to be
masked. Mask the data with "00” when the conversion data is positive and
with “11” when it is negative.
17