WAGO-I/O-SYSTEM 750 XTR
Process Image 39
750-563/040-000 2AO 0/4-20mA/ 6-18V DC/ 16Bit /XTR
Manual
Version 1.3.0
4.4.2
Step 2 – Y
1
User Scaling
The value for Y
1
is generated with the user scaling. The X
IN
value serves as the
input value for the user scaling. With user scaling switched off, the X
IN
value is
transferred unchanged to Y
1
.
The calculation is made taking into account the configured data format. The
significance of the result is determined by a gain factor and an offset.
Calculation formula:
Y
1
= X
IN
* GainAS / 256 + Offset
AS
The user scaling serves to adjust a required process value range to the analog
output range specified by the calibration.
In addition, it is possible to map the calibrated output range of 0 mA … 20 mA, so
that the analog value of 4 mA is output with a signed process data value of 0 and
currents less than 4 mA can be generated with negative process data values.
The calculation for the user scaling is carried out module-internally in the 32-bit
number range.
When user scaling is used, the required accuracy of the resolution of the analog
correcting range is changed, but not fundamentally limited. It is at the discretion
of the user whether the user scaling should be used or not. When Gain
AS
= 256,
the resolution remains unaffected in the 16-bit number range.
The value of 1/256 permits gain in the range of 0.0039 … 255.9960 and thus
gives the user scaling a very high variation range.
4.4.3
Step 3 – Y
2
Converting the Data Format
In this step, the value Y
1
determined by the configured data format is converted
into the DAC format, unsigned 16-bit integer. The context of the conversion is
described below:
Table 32: Converting the Data Format
Integer without
Leading Sign
Integer with
Leading Sign
Integer with
Leading Sign Bit DAC Format
0
−
32768
undefined
0
1
−
32767
−
32767
1
...
...
...
...
32768
0
0
32768
...
...
...
...
65535
+32767
+32767
65535
