Delta Tau Power PMAC Clipper, Руководство пользователя

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Power PMAC Clipper User Manual
Connections and Software Setup
34
Note
The explicit address register(s) can be found by subtracting Sys.piom
from
Clipper[0].Chan[0].AdcEnc[n].a
(n=0-3).
Note
The ADC input data must be in the “unpacked” format to be read
properly;
Clipper[0].Chan[0].PackInData = 0
.
Raw ADC Data (in bits)
Sys.WpKey = $AAAAAAAA; // Disable Write-Protection
Clipper[ 0 ].Chan[ 0 ].PackInData = 0 ; // Unpack Input Data all ADCs J3, J7
PTR ADCIN_1->S. IO :$900030.20.12; // ADCIN_1 J3 [bits]
PTR ADCIN_2->S. IO :$900034.20.12; // ADCIN_2 J3 [bits]
PTR ADCIN_3->S. IO :$900038.20.12; // ADCIN_3 J7 [bits]
PTR ADCIN_4->S. IO :$90003C.20.12; // ADCIN_4 J7 [bits]
Alternately use of bit shifting in PLC and Program with the structure,
Clipper[0].Chan[0].AdcEnc[n]
, as in:
Bit shifting example
// This method is most efficient and uses the least PMAC resources
GLOBAL MyAnalog1 = 0; // Global variable for shifted analog value initialized to zero
OPEN
PLC ExamplePLC
. . .
MyAnalog1 = Clipper[ 0 ].Chan[ 0 ].AdcEnc[0] >> 20; // shift right by 20 bits before assignment
. . .
CLOSE
Since the analog inputs have 12 bits of resolution (4,096 software counts) spanning over the full range of
the input voltage, wiring a ±10V voltage produces the following counts in software:
Single-Ended
[VDC]
Software
Counts
-10 -2048
0 0
10 +2048
Scaled ADC Data (in volts)
For general purpose usage, the ADC data (reported in bits) can be easily scaled and converted into “user”
voltage. In the example PLC below:

The global parameter ADCnZeroOffset represents the voltage offset with a zero volt input. This
is user adjustable.

The pointer ADCIN_n reports the raw ADC data in software counts, units of 12-bit (±2048).