RB8509 12-bit ADC
[Reference Manual]

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Detailed Description

Purpose

Measure a voltage.

Description

Module RB8509 is a 8-channel 12-bit analog to digital converter (ADC).

The module has eight analog inputs and a trigger input to start a data acquisition. A data acquisition can also be started by a software trigger.

Module RB8509 contains the following parts:

• a channel selector to select one of the eight inputs [ch0..ch7]
• a gain selector to select one of the four gains [1, 2, 4, 8]
• a 12-bit data Analog to Digital Converter

The following variations of this module are known to exist:

• 8-channel input, no external trigger input
• 4-channel input

The module's front-panels look as follows.

               8-channel               4-channel

 +----------------------+             +-----------+
 | A/D Converter 12-bit |             | 12-bit ADC|
 |                      |             |           |
 |    Adc 0     Adc 4   |             |           |
 |     (o) x     (o) x  |             |           |
 |                      |             | ch0 (o)   |
 |    Adc 1     Adc 5   |             |           |
 |     (o) x     (o) x  |             | ch1 (o)   |
 |                      |             |           |
 |    Adc 2     Adc 6   |             | ch2 (o)   |
 |     (o) x     (o) x  |             |           |
 |                      |             | ch3 (o)   |
 |    Adc 3     Adc 7   |             |           |
 |     (o) x     (o) x  |             | trg (o)   |
 |                      |             |           |
 |  RULBUS              |             |    RULBUS |
 +----------------------+             +-----------+

Configuration

At production time, the ADC is configured for unipolar or bipolar operation and its input voltage range is defined as 10 or 20V.

The following table shows the volt-per-bit values for the various input voltage ranges.

   Voltage range      |  volt-per-bit   bipolar
----------------------+--------------------------
   0    .. 10.2375  V |    2.5  mV        0
  -5.12 ..  5.1175  V |    2.5  mV        1
 -10.24 .. 10.235   V |    5    mV        1

Default configuration

rb8509_adc12 "name"
{
   address = 0xC0
   bipolar = true
   volt_per_bit = 5e-3
}

When the Rulbus configuration file is read, ADCs are configured as follows:

• external trigger disabled
• gain 1 selected
• channel 0 selected

Usage

Among others, there are functions to select channel and gain and to acquire and obtain the input voltage of the selected input.

int32     handle;
const int channel = 0;
float32   voltage = 0;

rb8509_adc12_open( &handle, "adc" );

rb8509_adc12_setChannel( handle, channel  );
rb8509_adc12_autoscale ( handle           );
rb8509_adc12_getVoltage( handle, &voltage );

rb8509_adc12_close( handle )

Open and close
EXPORT int32 RDL_API	rb8509_adc12_open (int32 *pHandle, CCstr name)
	open an ADC.
EXPORT int32 RDL_API	rb8509_adc12_close (int32 handle)
	close an ADC
Channel selection
EXPORT int32 RDL_API	rb8509_adc12_getChannel (int32 handle, int32 *pChannel)
	get currently selected channel [0..7].
EXPORT int32 RDL_API	rb8509_adc12_setChannel (int32 handle, int32 channel)
	select channel [0..7].
Gain selection
EXPORT int32 RDL_API	rb8509_adc12_getGain (int32 handle, int32 *pGain)
	get currently selected gain [1,2,4,8].
EXPORT int32 RDL_API	rb8509_adc12_setGain (int32 handle, int32 gain)
	select gain [1,2,4,8].
EXPORT int32 RDL_API	rb8509_adc12_autoscale (int32 handle)
	determine and set amplifier gain to fit current signal.
Data acquisition
EXPORT int32 RDL_API	rb8509_adc12_convert (int32 handle)
	start an analog to digital conversion.
EXPORT int32 RDL_API	rb8509_adc12_isReady (int32 handle, int32 *pFlag)
	true if result is available; flag is reset by reading result.
EXPORT int32 RDL_API	rb8509_adc12_getVoltage (int32 handle, float32 *pVoltage)
	issue software trigger and return input-voltage measured, may return 1 on timeout; OR wait for external trigger and return input-voltage measured.
EXPORT int32 RDL_API	rb8509_adc12_getValue (int32 handle, int32 *pValue)
	issue software trigger and return conversion value, may return 1 on timeout; OR wait for external trigger and return conversion value.
Triggering
EXPORT int32 RDL_API	rb8509_adc12_getExtTriggerLevel (int32 handle, int32 *pFlag)
	the current external trigger level.
EXPORT int32 RDL_API	rb8509_adc12_isEnabledExtTrigger (int32 handle, int32 *pFlag)
	true if external trigger-input is enabled.
EXPORT int32 RDL_API	rb8509_adc12_enableExtTrigger (int32 handle, int32 flag)
	enable or disable external trigger-input.
Configuration
EXPORT int32 RDL_API	rb8509_adc12_isBipolar (int32 handle, int32 *pFlag)
	true if ADC has bipolar configuration.
EXPORT int32 RDL_API	rb8509_adc12_getVoltperbit (int32 handle, float32 *pVpb)
	the ADC's input sensitivity configuration.

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