The DAC device is used to manage an analog output with +/- 10V and a 16bit resolution. Its main characteristics:

• setting in bit of the voltage to generate in output

• setting an offset to the output voltage

• setting a minimum and maximum limit to the output voltage

• inversion of the output voltage value sign

The INTDEVICE section in the configuration unit must have the declaratopm pf the hardware resources needed to use the DAC device. At least one analog output must be present. In the INTDEVICE section of the configuration unit the following definition must be added:

;---------------------------------
; Device definitions
;---------------------------------
INTDEVICE
<device name>  DAC  <IOutA>

where:

	Unlike other devices, the DAC device does not need a sampling time since it merely converts the input data and updates the output only when the data is entered.

Example

;---------------------------------
; Devices definitions
;---------------------------------
INTDEVICE
AnOut DAC  2.AN01

Block chart of the device:

The DAC device, since it works with 16 bit resolution, accepts input values between -32768 and 32767. The output voltage is proportional to the value entered by the user. The device has a symmetrical behaviour around the zero analog voltage at less than any offset value entered. The minimum and maximum analog voltages can be set by the lowlim and uplim parameters, always remaining within ±10V:

• 32767 –> +10 V (maximum permitted),
• -32768 –> -10 V (minimum permitted).

The value introduced in the device to obtain an analog voltage VOUT is calculated by the proportion:

• for positive values: in = (VOUT * 32767) / 10,
• for negative values: in = (VOUT * 32768) / 10.

The commands provided to manage the device are listed below: the device executes the commands in the order they are received.

This section gives an abstract of code lines as an example in the first steps of using the device in question. As explained, the first step is to declare the device in the configuration unit. Then a new QCL unit can be created for writing the the code to command the controller. The code lines and comments below are examples of some simple operations executed by the device.

[...]
BUS
    1   1K31F   30
    2   .       .
    3   1MG8F   .
    4   .
 
INPUT
  ifChangeOut F 3.INP01 ;Output voltage change command
 
INTDEVICE
  AnalogOut DAC 3.AN01

SYSTEM
  slOutAna    L IN         ;Variable for analog output
 
GLOBAL
  gfChange    F         ;Rise edge flag
 
BEGIN
  ; Initializations
  AnalogOut.offset = 0 
  AnalogOut.uplim = 32767      ;Max analog output as 10V
  AnalogOut.lowlim = -32768    ;Min analog output as -10V
  AnalogOut.OUTDIR             ;Set the right analog output sign
  WAIT NOT AnalogOut.st_outrev ;WAIT the right state
  slOutAna = 0                 ;Set the variable as 0V
MAIN:
  IF ifChangeOut
    IF NOT gfChange;Wait for input activation
      gfChange= 1 ;Set the change made flag 
      AnalogOut.in = (slOutAna * AnalogOut.uplim) /100 ;Set the device analog output
    ENDIF
  ELSE
    gfChange = 0 ;Reset the change made flag
  ENDIF
 
  WAIT 1
  JUMP MAIN
 
END

When the ifChangeOut input is activated, on the rise front, the output voltage value is updated by the declared DAC device (here named AnalogOut). The voltage value in tenths of a volt is contained in the slOutAna variable. Another unit in the project can access the slOutAna variable and set the required value.