A Unique Menu Driven System for a Broad Range of Data Acquisition and Custom Control Applications
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Operator interface to the DLC is through a computer or hand terminal (locally by RS232 serial or remotely through use of modems). |
The DLC system couples the latest micro-computer technology and analog/digital electronics with customized software. This system provides a range of support for the most casual of users to the requirements of the most demanding. For most data collection operations, use of the menu driven operational control program is all that is needed to configure the system parameters and to collect data. Where data conversions or specific output control is required, equations or control programming may be added to the DLC operational control program in the form of simple BASIC language statements.
The DLC software platform is implemented as a BASIC language interpreter with numerous data acquisition and control extensions to the language. Performance critical functions are implemented in machine code for the best possible performance. A feature of the DLC system platform is that it allows you to either extend the DLC operational control program or create your own program(s) to tailor the menus, user interface, or operational characteristics uniquely to your needs, all in the BASIC language .. The DLC provides for 30K bytes of BASIC language programming space (much like running a BASIC program on a personal computer). Programs or data can be stored or loaded using optional solid-state credit card sized memory cards.
REM Convert Linear Temperature Sensor
REM (Kelvin) Output to Fahrenheit
10101 X(2)=-463.4472+.1788618*X(2)
REM Heater Control (Digital Output 5)
10102 IF X(2)>73 THEN DIG W,5,0
10103 IF X(2)<69 THEN DIG W,5,1
If temperature (channel 2) goes below 69 (degrees F) then turn heater on. If temperature goes above 73 then turn heater off.
Gain | Range | Resolution | Noise (RMS) | Accuracy (%FS) |
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The range/resolutions can be extended by installing the PG - Programmable Gain (1,10,100, & 1000X) Feature Card. Chopper stabilized amplifier used to amplify signal but keeps noise amplification to a minimum (4x for noise at 1000x for signal).
Additional range/resolutions/noise/accuracies are then:
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Autoranging is supported. The DLC can automatically select the best range and gain (particularly useful if range is not known ahead of time).
The number of data points for each memory configuration is:
Memory Size | Number of data-points |
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There is a backup power capacitor for the RAM which will allow retention of data for up to several hours after the power source has been removed from the DLC. This allows batteries to be changed or allows for short power-outages without loss of previously collected data.
Strategic program locations (BASIC language GOSUB locations) have been reserved for user-written code. These locations functionally serve as pre-scan, mid-scan, post-scan, and post-integration hook locations. This allows the user to add program statements to tailor the DLC’s logging or controlling operation for unique operations. For example, if a 10 second delay was required to turn on external device and allow the device/sensor/system to reach steady state, that delay would be added as pre-scan code such as:
12750 DIG W,1,1 REM Turn on device on digital output 1.
12751 TIME=0 REM Set internal second timer = 0
12752 IF TIME<10 THEN 12752 REM Wait for 10 seconds
12769 RETURN REM Continue (perform scan)
Mid-scan hooks would typically be used to program sensor conversion equations (convert from millivolts to sensor type units) and/or output control statements. Converted values from the mid-scan hooks are then the data values stored. If no conversion equations have been programmed then the millivolt reading is stored as the data value.
Post-scan hooks would typically be used for scan-clean up activities.
Likewise, Post-integration hooks may be used for activities that may need to be done after an average of scans is completed.
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