9323 Hamilton Mentor, Ohio 44060 - USA Tel:+1-440-357-1400 Fax:+1-440-357-1416

Scientific Solutions ^® Inc.,

LabMaster ^® DMA

Product Description

The LabMaster DMA turns your PC into a powerful industrial/scientific workstation.  The LabMaster DMA supports a range of high-performance, low-cost, multifunctioned analog and digital I/O functions including analog-to-digital conversion, digital-to-analog conversion, digital I/O and timer/counter functions.  The newly designed version includes a reduction in board size by using surface-mount and custom ASIC technology; an increase in the resolution of the timer/counters; and a newly designed convenient desktop signal connection enclosure.  Other features include 16 analog input channels, dual analog outputs, 24 digital I/O lines and five 16-bit timer/counters with 250ns resolution.

The LabMaster DMA consists of a single-slot PC Expansion Board and an External Unit containing the A/D converter circuitry and convenient signal connections. The external unit provides access to remote analog sources.  This arrangement optimizes the analog signal clarity providing the most accurate readings. The external ADC allows precision measurement of small analog signals avoiding the inherent noise inside the PC. The LabMaster DMA is the first data acquisition system with the external ADC design for ultra low-noise measurements..

The LabMaster DMA is available in several models that vary according to A/D resolution and speed, programmable amplifier gain settings, and digital I/O buffering methods.  The external modular design of the analog conversion circuitry permits retrofitting to higher resolution and faster conversion rates as measurement requirements change.  The standard 16 analog input channels can also be increased to 256, with optional expansion modules.

Scientific Solutions produced the worlds first IBM PC based data acquisition products in 1981 and has shipped million of cards since.  The LabMaster family has been available longer than any other PC data acquisition product in the world.  Updates and enhancements throughout the years, has provided the LabMaster with the most current technology while maintaining 100% compatibility with the original - important for maintaining users substantial software investment and knowledge of the product.

Our Solution Includes

• LabMaster DMA PC Interface - Data Acquisition & Control interface for inside the PC
• LabMaster DMA A/D unit - External "low noise" desktop Acquisition unit
• LabMaster DMA Handbook
• LabMaster Series Software - A collection of routines and test procedures (Included with LabMaster DMA)
• Test software

Key Features

• ADC external to computer for ultra-noise-free measurements
• ADC sampling options from 1hz to 160Khz, 12bit and 16bit resolution.
• Accurate, timed ADC use with channel auto-scan for Burst Mode performance
• Reliable DMA for background A/D conversion
• Two 12-bit DACs with 4-20mA current loop & 5 selectable voltage output ranges
• 24 lines of buffered digital I/O - monitor switches, drive relays, solenoids or LEDs
• Five high speed, 16-bit Timer/Counters for precision acquisition and frequency measurements
• Software programmable gains from 1 to 500.

Applications

• Energy Management
• Chromatography
• BioMedical (neuron stimulation, muscular stress)
• Psychology (infant stimulation, stimulus/response, interval timing, Galvanic skin response)
• Process Automation (relay control, stepper motor control, timing/counting, die cutting monitor)
• Test and Measurement (PC board tester, particle counter, component solderability determination)

Functional Description

The LabMaster DMA is a complete data acquisition & control product. A PC Interface, containing all the digital I/O and analog output circuitry, installs internally into the PC. A shielded cable connects this board to an external desktop unit containing the analog-to-digital (ADC) converter. The sensitive A/D conversion is isolated from internal PC electrical noise and located near equipment supplying the analog input.

Overview of Product Options

The LabMaster DMA is a very versatile family of data acquisition products and as such there are many different options available.  An understanding of these options are necessary to correctly choose the configuration best suited for your particular needs.  The Functional Description in this document contains detailed discussion about the various choices and is recommended reading.

Software Reference Chart identifies the correct LabMaster version required for a number of specific software packages.

The LabMaster DMA is available in several different models.  The differences among these models are: A/D speed, analog input gain options, type of Digital buffering, and method for external signal connections.  The options (with hyperlinks to the appropriate section) can be summarized as follows:

1. Analog-to-Digital Converter Speed.
   • Choices are 50Khz or 160Khz
2. Analog-to-Digital Resolution
   • Choices are 12bit or 16bit
3. Analog-to-Digital Converter Gain Settings
   • Choices are HG, PGL or PGH.
4. Digital I/O Buffering Technique
   • Choices are Inverting or Non-inverting
5. Method for external signal connections
   • Many different options available including
   • Ribbon Cable Connections
   • Screw Terminals
   • 3.5mm MiniJack
   • BNC connections
     

Analog-to-Digital Conversion (ADC)

Analog signals in the ±10 Volt range are digitized by an Analog-to-Digital Converter (ADC). Designed to deliver flexible data, the ADC configures for Input Mode (16 single-ended, 8 true differential, or 16 pseudo differential), Input Range (unipolar or bipolar), Operating Mode (normal, overlap), Channel Auto-Scan, Gain, and Output Format (two's complement or binary). A variable gain amplifier at the input to the sample and hold circuit allows the input range to vary from ±10 mV to ±10 V. Configured by software, a conversion can be initiated by a software command, a rising edge from one of the on-board timer/counters or a rising edge from an external source. The end of a conversion can be detected using a hardware interrupt or polling the status register. Data is transferred at the end of a conversion by reading the data latches or automatically using DMA.

The LabMaster DMA has the A/D circuitry located external to the computer.  Throughout the years many different ADC modules have been offered by Scientific Solutions.    The current 50Khz and 160Khz ADC modules replace the previously offered 40Khz and 100Khz versions.  These new versions remain 100% compatible with the previous versions while offering increased analog input sampling rates.  The speed of the converter determines how fast you can sample your analog signals.

Choices for ADC speed are 50Khz or 160Khz.  Contact Scientific Solutions regarding any special requirements.

Analog-to-Digital Resolution

The LabMaster DMA comes with either 12bit or 16bit A/D resolution.  The higher resolution allows measurements of smaller voltage changes.  For example, a 12bit A/D configured for 0 to 10v has 2.44mv / bit.  This means the ADC can measure changes as small as 2.44 millivolts.  Of course, if you also use an on-board gain of 10 (with a PGL module), then the input signal into the gain amplifier can be as low as 0.244 millivolts to be detected by the ADC.  The 16bit converter is accurate to 2 LSBs - this means the data is treated as 16bit data, but the least two significant bits are not guaranteed.  With a gain of 1, the 16bit module can measure changes as small as 0.610mv for the 0 to 10v range or 0.0610mv with an on-board gain of 10 used. The application program needs to know the resolution of the A/D so it can properly convert "bits" to "volts".

Choices for ADC resolution are 12bit or 16bit.  Contact Scientific Solutions regarding any special requirements.

Analog-to-Digital Gain Options

For the best measurements, the analog input signal to be measured should be as close to the A/D range as possible.  This ensures that the resolution of the A/D is being properly used.  In unipolar mode, the A/D range is 0 to +10v.  In bipolar mode, the A/D range is -10v to +10v.  If for example, the analog input signal to be converted is from 0 to +5v, then you would want the A/D to be in unipolar mode and have a gain of 2 (using on-board PGH gain).  The LabMaster DMA has the capability to have hardware gains or software programmable gains.  Hardware gains (HG) are set by jumpers or external components.  Software programmable gains (PG) are set by the software.  A gain set by hardware will effect all the input channels the same.  A gain set by software can be changed "real-time" to have different gains on a channel-by-channel basis.

HG stands for Hardware Gain. This version ships from the factory with all analog input channels at a gain of 1.  There are two versions of the HG module, referred to as HGI and HGE.  HGE is our standard configuration for hardware gain.  In either case, the gain is set by hardware and is the same gain for all the channels.:

HGE version permits you to change the gain for all the channels to any value by adding a precision resistor on the external ADC board.  This was the configuration of the previously offered 40Khz non-programmable gain version.  The 50Khz and 160Khz come standard as HGE. (note: modules labeled as 50Khz or 160Khz "HG" are really "HGE").

HGI version has precision gain resistors already included with predefined gain settings of 1 or 2 (input ranges of  +/-10v, 0 to +10v, +/-5v, 0 to +5v) set by changing jumpers.  The precision resistors are internal to the module and are factory matched to track over time and changes in temperature.  This was the configuration of the previously offered 100Khz module and 125Khz module.  (note: modules labeled as 125Khz "HG" are really "HGI")

PG stands for Programmable Gain. There are two versions of the PG module, referred to as PGL and PGH.  In either case, the gains are under software control and can be changed "real time" on a sample-by-sample basis.

PGL stands for Programmable Gain Low.  This version has software programmable gains of 1, 10, 100, 500.  It is called PGL, Programmable Gain Low, because it is intended to be used with low level signals that need higher gains.

PGH stands for Programmable Gain High.  This version has software programmable gains of 1, 2, 4, 8.  It is called PGH - Programmable Gain High - because it is intended to be used with high level signals that need lower gains.

Choices for gain include HGE(external resistor selected to any),  HGI(internal resistors selected for 1 or 2), PGL(1,10,100,500) or PGH(1,2,4,8). Contact Scientific Solutions regarding any special requirements.

Analog-to-Digital Conversion - Feature Summary

• Resolution: Depends upon module (12bit or 16bit)
• Maximum sampling rate: Depends upon module (50Khz or 160Khz
• 16 Single-ended or 8 Differential input lines. Expandable to 256SE / 128DI
• Selectable input range
  • 0 to +10 Volt (example: unipolar, 2.44mV/count (12bit) )
  • ±10 Volt (example bipolar, 4.88mV/count (12bit) )
• Choice of A/D trigger (software controlled)
  • Timed intervals using pacer clock
  • Maximum rate channel scans at timed intervals
  • External trigger (TTL pulse, rising edge)
  • Software initiated strobe
• Auto-scan on blocks of consecutive channels
• Latched data transferred using:
  • Programmed I/O
  • Direct Memory Access (DMA)
• DMA transfer of samples using levels 1 or 3
• Hardware interrupts - selectable from IRQs 2,3,4,5,6,7,10,15 - software enabled
  • End of Conversion
  • A/D Data Overrun
  • DMA Terminal Count
• Analog Input Gains:
  • 1,2,4, or 8 software programmable gains (LabMaster PGH 50Khz or 160Khz)
  • 1,10,100, or 500 software programmable gains (LabMaster PGL 50Khz or 160Khz)
  • Gain 1 to 1000 using external precision resistor (LabMaster - 50Khz,160Khz HG/HGE)
  • Gain 1 or 2 using external jumpers (LabMaster 125Khz HG/HGI)

Digital-to-Analog Conversion (DAC)

The two independent, 12 bit D/A converters individually configure for one of five voltage ranges. Each DAC can also be set to support a 4-20mA current loop. The voltage and current outputs are available on separate connectors. The voltage output from a DAC is changed by writing a low and a high byte to two I/O locations. The value of the high byte is saved until the low byte is latched to insure all 12 bits reach the DAC simultaneously.

Features

• 12 bit resolution (4096 equal intervals)
• Two independent converters
• 5 microsecond settling time (full scale)
• 200 Khz maximum output rate (software controlled):
• Choice of voltage or 4-20mA current loop output
• Five jumper selectable voltage output ranges:
  • ±2.5 Volts, ±5 Volts, ±10 Volts,
  • 0 to +5 Volts, 0 to +10 Volts

• Current loop outputs
  • Available on both channels
  • Floating or Ground Loop Supply
  • Voltage compliance: 8V to 36 V

System Timer/Counter (STC)

Five independent 16bit timer/counters count TTL compatible pulses (rising or falling edge) generated from a wide range of equipment and sensors. Each gateable counter counts up or down (binary or binary coded decimal format - BCD). The accumulated count may be read at anytime without disturbing the counting process. Each of the counters can be connected to others to form a counter with resolution up to 80 bits. The counters can be driven by an on-board 1MHz, 2MHz or 4Mhz crystal (software selectable) giving them resolutions from 250nsec to 10milliseconds. If driven externally, the counter/timers can count events at speeds to 6.25Mhz.

A TTL compatible pulse/level output signal is available for each counter. All signals are located on a 50-pin header connector.

Timing/Counting - Feature Summary

• Five independent 16bit counters.  Can work independently or cascaded.
• Five on-board sources for interval timing to 250nanosecond resolution (4MHz oscillator)
• Event Counting to 6.25MHz (160 nanosec.intervals)
• 15 external I/O connections
  • 5 outputs (1 TTL load - pulse or level)
  • 5 source inputs (TTL compatible pulses)
  • 5 gate inputs (TTL edge or level, control counting or serve as input signal)
• Counter outputs can:
  • Trigger A/D conversions
  • Trigger hardware interrupts - selectable from IRQs 2,3,4,5,6,7,10,15 - software enabled
  • Send square and complex waveforms
  • Gate counters
  • Drive TTL devices
• 50-pin opto 22 compatible connector

Digital Input/Output (DIO)

The 24 lines of TTL compatible I/O are addressable in groups of eight (24 input, 24 output, 8 input/16 output, 16 input/8 output or 12 input/12output). All outputs are latched. Simple input is unlatched while strobed inputs are latched. A 50 pin I/O module compatible header connector provide access to industry standard solid state relays, isolation modules and screw terminals. Between the connector and the 24 I/O lines are pull-up resistors and sockets that accept 74LSxxx for buffering.

Digital I/O - Buffering Options

The LabMaster DMA has 24 lines of Digital I/O available with Universal Socket Sites (USS) for installation of buffering devices.  When you order your LabMaster DMA you can specify to either have Inverting Buffers or Non-Inverting Buffers installed and tested by the factory.  Since the buffers are socketed, you can change the buffering type in the future if your needs change.  Also, you can change which digital lines are inputs and outputs by changing the mode (position) of the buffers.  Normally the software you will be using with the LabMaster will specify the type of buffering you need.

Inverting Buffer: Output Mode: If the software writes out a logic '1' (5 volts) to a digital output, then this value is inverted by the buffer and a logic '0' (0 volts) is presented to the outside world.  This type of buffering is popular for installations and software packages that connect solid-state-relays to the digital outputs.

Input Mode: If an external source supplies a logic '1' (5 volts) to a digital input, then this value is inverted by the buffer and a logic '0' (0 volts) is presented to the software.

Non-Inverting Buffer: >Output Mode: If the software writes out a logic '1' (5 volts) to a digital output, then this value is not changed and a logic '1' (5 volts) is presented to the outside world.

Input Mode: If an external source supplies a logic '1' (5 volts) to a digital input, then this value is not changed and a logic '1' (5 volts) is presented to the software.

Choices for Digital I/O Buffering include Inverting or Non-Inverting.  Note that in the past the LabMaster DMA was factory configured for either inverting or non-inverting.  As of January 1, 2000 all LabMaster DMA PC Interfaces are configured for non-inverting, with the extra inverting buffers also supplied - providing the customer with both options!

Digital I/O - Feature Summary

• 24 Lines of TTL compatible input/output
• Software programmable I/O in groups of eight lines
• Supports all three 8255A operational modes
• Hardware interrupts - selectable from IRQs 2,3,4,5,6,7,10,15 - software enabled

Handshake strobes for Digital I/O available when used in strobed I/O modes (Mode 1 or Mode 2)

• Universal socket sites allow installation of a wide variety of standard driver and receiver chips
• Data transfer at rates up to 200KHz (actual rate depends on software)

50-pin opto 22 compatible connector

Technical Specifications

Frequently Asked Questions

volts = (count) * (range) / (gain) / (2 raised to the power of "resolution")

Example: count of 3FFFh, range of -10v to +10v, gain = 1, resolution of 16bit:

note: 3FFFh = 16383 decimal

volts = (3FFF) * (20) / (1) / (2 raised to the power of 16)

volts = (16383) * (20) / (1) / (65536)

volts = 4.999

Q6. How do I determine the decimal value for a particular D/A output voltage?

A6. The DAC data is always Two's Complement.  The equation you use depends upon if the DAC range is configured for Unipolar (0 to +10 or 0 to +5) or Bipolar Range (-10 to +10, -5 to +5, or -2.5 to +2.5).
Note that LabPac32 ALWAYS EXPECTS the data to be provided as if you have a 16-bit DAC, even if you actually only have a 12-bit DAC.  This is because LabPac32 calls are common among all the Scientific Solutions products.

For LabPac32 calls:
Bipolar Range: Dac Data = 65535 / Range * Voltage
Unipolar Range: Dac Data = (65535 / Range * Voltage ) - 32768

Where Range = Output Voltage Max - Output Voltage Min
Example: DAC configured for -10v to +10v Range
voltage range = Vmax - Vmin = 10 - (-10) = 20
Dac Data = 65535 / 20 * voltage
Dac Data =  3276.75 * voltage
For Output of +5 volts, Dac Data = 3276.75 * 5 =  16383.75, take the Integer of the number = 16384

Bipolar Range:

Dac Data = Integer of  { (voltage)* ( (2 ^resolution -1) / range) 

Example for 12bit module configured for the range of -10 to +10 volts:
Dac Data = [ (voltage) * ( (2 ^resolution -1) / range) ]
Dac Data = [ (voltage) * ( (2 ¹² -1) / 20) ]
Dac Data = [ (voltage) * ( (4096 -1) / 20) ]
Dac Data = [ (voltage) * 204.75 ]

Then, for an output voltage of 5 volts, the data would be
Dac Data = [ 5 * 204.75 ]
Dac Data = [ 1023.75]
Dac Data = which you convert to an integer and get the value of 1024

Then, for an output voltage of 2.5volts, the data would be Dac Data = [ 2.5 * 204.75 ]
Dac Data = [1023.75]
Dac Data = which you convert to an integer and get the value of 1024

Then, for an output voltage of 2.5 volts, the data would be
Dac Data = [2.5 * 204.75]
Dac Data = [ 511.875 ]
Dac Data = which you convert to an integer and get the value of 512