Daqarta for DOS Contents
DT2821 CONFIGURATION PARAMETERS:
PARAMETER OVERVIEW:This Daqarta driver allows you to specify certain parameters on the DT2821.ADC line, which must be the second line of the DQA.CFG file. Each parameter is given as a letter and colon, followed immediately by a value or text string. Use a space between parameters. For example:
DT2821.ADC A:h300 I:5 M:21FSThe order of the parameters is not important for this driver. The parameter letters are case-insensitive, as are the entries that follow the colons.
Daqarta does not use any SET lines in your AUTOEXEC.BAT file, nor does it use any non-Daqarta drivers or libraries that may have been supplied by Data Translation or others.
You can check to see which parameters have been set, either via the configuration line or by default, by checking the board information summary available via the ALT-H Plug-In Help system. This also shows a summary of the default values for all parameters. There is no need to enter any parameter that is the same as the default value assumed by Daqarta.
A: ADDRESS:Use this to tell Daqarta the base I/O address for your board. This should match the value selected by jumpers on the board, which is typically shipped by Data Translation with a default setting of 240h (hexadecimal). This is also the default address assumed by Daqarta if you omit the A: parameter. To tell the Daqarta parameter parser that a value is in hexadecimal, precede it with an 'h', as in:
DAS20.ADC A:h300The value you enter is not validated against any standard list. Daqarta looks for the board at the address given, and if it does not find a valid DT2821-series board there it exits with:
'DT2821-series board not found.'
The only exception is if you set A:0 to allow viewing of this board Help system without having a board installed or properly configured.
The DT2821-series uses jumpers W15 - W18 to set the base address. These jumpers form a binary-weighted value with each jumper IN counting for 0 and OUT counting as follows:
W15 = 100h W16 = 80h W17 = 40h W18 = 20h
There is also an implied 200h that is always present. So the total possible address range is from 200h (all IN) to 3E0h (all OUT). The 240h factory default is:
200h = 200h (always) W15 IN 100h = 0 W16 IN 80h = 0 W17 OUT 40h = 40h W18 IN 20h = 0 TOTAL: 240h = BASE ADDRESSOnce Daqarta is running, the ALT-H summary screen will show the value of the base address in use.
C: CHANNEL PRESET, SE/DI SETTING:The C: parameter tells Daqarta to start up with a given input channel. For example:
DT2821.ADC C:3would set channel 3. You may change the Channel from the Board control menu during operation. If you don't give a C: parameter, the default is channel 0.
The range of allowable channel values depends upon the model (as set by the M: parameter) and on the position of the Single Ended / Differential Input jumpers W3 - W6, if applicable to that model. For the straight DT2821 the jumpers select between 16 SE channels 0-15 or 8 DI channels 0-7 (factory default).
The status of the jumpers is not directly readable via software, so you need to tell Daqarta which way they are set. If they are set to SE, use an S in front of the selected channel number, as in:
This sets the same initial channel as the previous example, but allows the Channel control in the menu to range from 0-15 instead of the assumed DI factory default of only 0-7. Note that there is no effect upon the hardware itself.
You can use the C:Dn form to specify DI mode, even though DI is the assumed default. This can serve as a reminder to yourself or others in your lab, since there is no simple way to tell which way the jumpers are set from outside the system.
A model without selectable SE/DI modes will automatically be limited to the appropriate channel range for that model, as determined by the M: parameter.
If you use the C:Sn parameter on a model that only has differential inputs, Daqarta will exit with:
'No SE capability on specified Model.'Or if you use C:Dn on a model with only SE inputs:
'No DI capability on specified Model.'
If you set a channel number that is too high for the SE/DI mode and model, Daqarta will exit with:
'Specified channel exceeds DI limit on this Model.'Or if you set C:Sn too high on models with only 4 or 8 SE channels:
'Specified channel exceeds SI limit on this Model.'
Once Daqarta is running, the ALT-H summary screen will show whether the mode is Single-Ended or Differential.
D: DMA (Direct Memory Access) Level:The DT2821-series boards use DMA for acquisition and signal generation in most modes. The D: parameter specifies DMA level 5, 6, or 7. This must match the FIRST DMA CHANNEL jumper settings for DMA REQUEST (W19 and W20) and DMA ACKNOWLEDGE (W23 and W24).
The factory and Daqarta default is level 5. The setting can't be read directly from the board via software, so if you need to use another level, use a DQA.CFG line like:
Levels 5 or 6 can be set via simple jumper plugs, but level 7 requires wire jumpers:
DMA REQUEST DMA ACKNOWLEDGE DMA o W19 o W20 o W21 o W22 o o W23 o W24 o W25 o W26 o 5 o-jmp-o o o o o-jmp-o o o o 6 o o-jmp-o o o o o-jmp-o o o 7 o o o o o o o o o o \-----wire------/ \-----wire------/The second DMA channel (W21-22 and W25-26 posts) is ignored by Daqarta, and may be used by another device. However, note that most other software for the DT2821 series will expect to use the second channel. This second DMA channel is not independent of the first, and using both together only serves to simplify the software for buffer management of a single ADC or DAC process. (Back when this series was designed, there was not such a demand for DMA channels as in current systems; the dual-DMA approach probably seemed like a reasonable way to manage DMA buffers.)
F: HELP FILE OMIT:Daqarta normally attempts to load this associated Help file on start-up, and exits with an error message if it can't find it. Setting F:0 on the ADC configuration line tells Daqarta not to look for the file. You would probably only want to use this option if you are really short of DOS memory, since loading the Help file only increases memory use by a few hundred bytes for its separate link stack and directory. (The file itself shares the text buffer of the Main Help file.)
Note that ALL Help files, including main, can be omitted via an F:0 parameter on the INIT line (first line) of the DQA.CFG file. If this is present, no individual module Help will be loaded.
I: IRQ (Interrupt ReQuest):The Interrupt Request level for a DT2821-series board may be set to 3, 5, 7, 10, or 15 (default). The actual level is set by a single jumper in the W27-W31 block on the board:
IRQ Jumper 7 W31 5 W30 3 W29 15 W28 (Default) 10 W27This setting can't be read directly via software, so if you set anything other than the factory default IRQ 15, you must tell Daqarta via the I: parameter. For example, if you set IRQ 5 then the .ADC line in your DQA.CFG would look like:
For maximum performance with STIM3 outputs in RTime mode, you may want to avoid IRQs 10 and 15. These IRQs use the system's second interrupt controller, which requires an extra End Of Interrupt (EOI) command to acknowledge each interrupt. This takes a little more time and could reduce the maximum sample rate possible in interrupt-driven operation, which is only used when STIM3 outputs are active in RTime mode. The extra time will have no effect on normal DMA RTime (ADC only) or on Sequential mode (with or without STIM3 outputs).
If you use interrupt-driven RTime, you may need to use the special DDISK13 BIOS-replacement driver for DDisk recording. This will only work with drives of 528 Meg or less. For larger drives, you will need to conduct your own tests to see if you can get suitable glitch-free recordings at your chosen sample rate, etc.
M: MODEL:This notifies Daqarta if your board is other than the default basic DT2821 model. (There is no way for this information to be read directly from the board via software.) For example, to tell Daqarta that the board is a DT2821-F-16SE model, the .ADC line (second line) in your DQA.CFG file might look like:
DT2821.ADC M:DT2821-F-16SEor it could use the shorthand form:
DT2821.ADC M:21FSThe shorthand form for each model is shown in the second column of the Models and Features table in the Introduction. Setting the Model tells Daqarta to assume the features and speeds shown there, which are Data Translation specifications. You may want to override the ADC and DAC maximum speeds via the S: (Speed) parameter.
O: OUTPUT DAC RANGE (Reference Only):For most models with DACs, Data Translation allows selection of the individual output range for each DAC. (Models DT2823 and DT2829 have 16-bit DACs with a fixed +/- 10 Volt range.) The ranges are set with jumpers, as shown:
- Jumpers - --------- RANGE, Volts ------------ DAC1 DAC0 +/-10 +/-5 +/-2.5 0-10 0-5 W11 W7 - - IN - IN W12 W8 - IN IN IN IN W13 W9 IN IN IN - - W14 W10 IN - - - - (Default)You can use the O: parameter to tell Daqarta which DAC ranges have been set, and they will be reported on the ALT-H summary page as a convenient reminder. (The jumper settings can't be read directly via software.) Use the O: parameter with one of the following ranges:
B10 Bipolar 10 Volts B5 Bipolar 5 Volts B2.5 Bipolar 2.5 Volts U10 Unipolar 10 Volts U5 Unipolar 5 VoltsFor example, to indicate that both DACs are set to +/- 5 Volts you would use:
If you set the individual DACs differently, put the DAC number just after the colon. For instance, with DAC 0 set to +/- 5 and DAC 1 set to 0-10 Volts, use:
DT2821.ADC O:0B5 O:1U10
In general, you will probably want bipolar ranges for most work, since then the output will be 0 Volts when it is off. For unipolar ranges Daqarta will provide a half-scale offset so that sine waves swing between 0 at negative peaks and the maximum value (5 or 10 Volts) at positive peaks.
Note that values you set with the O: parameter are strictly for your own reference. Daqarta actually ignores the ranges you specify here, since they pertain only to the analog gain of the DAC outputs, not to the digital values Daqarta uses to control the waveforms. If you specify different ranges than have been set via the jumpers, the waveforms will still be correct even if their levels are not as shown on the summary screen.
P: PORT I/O (DIO) CONFIGURATION:All DT2821-series boards have 16 digital I/O (DIO) lines. These are accessible as two ports of 8 bits each, designated DIO Port 0 and Port 1. Daqarta uses one port for input and the other for output, with the default being Port 0 for output. (Think of "0 = O for Output", or "1 = I for Input".) If you need to reverse these, perhaps for compatibility with existing wiring or other software that uses this board, use the P: parameter with the letter O after the colon and give the Output port, as in:
DT2821.ADC P:O1This would specify Port 1 as Output, so Port 0 would become the input automatically. You never need to give the default of P:O0, but you could do so as a reminder to yourself when reviewing the DQA.CFG file. The current setting is also shown on the ALT-H summary screen when Daqarta is running.
The Board control menu allows selection of digital I/O bits for various functions. You will typically hard-wire these items once your system is set up, so it makes sense to preset these bit assignments at start-up. The P: parameter allows you to specify bit usage other than the defaults.
Use a letter after the P: to specify usage, followed by a digit (n) from 0 to 7 to specify the bit for that use. (Letters are not case-sensitive.)
Parameter ---- Usage ---- Default P:En External Trigger Dig In 0 P:Dn DDisk Remote Dig In 1 P:An Averager Remote Dig In 2 P:Pn Pulse Output Dig Out 0Make sure that inputs don't use the same bit. Pulse Output can use any bit, since it is the only output here. (However, note that it will be superceded when STIM3 Stimulus Generator DigOut is active.)
R: INPUT RANGE PRESET:Use this parameter to specify the initial input Range control setting, and also to tell Daqarta about certain jumper settings that affect range sensitivity or data format.
Most models allow the input range control to select one of 4 different input ranges. Depending on the model, these are from the standard PGH ranges or the low-level PGL ranges, as indicated in the Models and Features table.
PGH: PGL: 10 10 5.0 1.0 2.5 0.1 1.25 0.02
Models DT2821-G-16SE and DT2821-G-8DI use the PGH range series, but also allow jumper selection of an additional 2x gain applied to all ranges. Similarly, the DT24-EZ-PGL normally uses the PGL ranges, but these may also be doubled:
PGHx2: PGLx2: 5.0 5.0 2.5 0.5 1.25 0.05 0.625 0.01By default these are bipolar ranges, but most models also allow these same maximum values in a unipolar format via jumper selection. This would convert the +/- 10 Volt bipolar range to 0 to 10 Volts unipolar, for example. Unipolar operation is not recommended for use with Daqarta, but may be needed for compatibility with other software that must run on the same system.
Boards are set to the +/- 10 Volt range by default. If you want to set +/- 5 Volts instead, for example, you can use:
DT2821.ADC R:5If you have a standard PGH-type model, Daqarta will know that this is the second-highest of the four programmable ranges, where the top one is +/- 10 Volts. Daqarta will thus start up with the second range active and show +/- 5.0 V for the Range item, and allow you to change the range up to +/- 10 V or down as far as +/- 1.25 during operation.
If you have a DT2821-G-16SE or -8DI model, Daqarta will assume the same thing. But if you have set the jumpers for the x2 configuration, there is no way for Daqarta to read that status directly from the board. You must tell Daqarta that this 5 Volts is the top range of an x2 series and not the second range of the standard series, by using:
If Daqarta is not told about the x2 jumper, you will get the wrong range selection. This is only needed where there is ambiguity about the x2 jumper: If you give
DT2821.ADC R:0.625then Daqarta assumes that you must have set the x2 jumpers, since that is the only way you could get this particular range. With the DT24-EZ-PGL you never need the 'X' because there is only one way to get any given range, so Daqarta can always infer the relevant jumper setting.
Daqarta also assumes any range value you give is a bipolar range. If you have set the unipolar jumper configuration (which also can't be read directly from the board), then you must tell Daqarta via a U after the colon, as in:
Note that the DT2821-G-16SE and -8DI models don't allow both x2 and unipolar jumpers. The DT24-EZ-PGL does allow both together, but only the 'U' is needed, not an 'X' as well, because as mentioned earlier Daqarta can always infer the relevant x2 setting from the range value.
In addition to the range preset and the presence of x2 or unipolar jumper settings, you also use the R: parameter to tell Daqarta about the data format used by the ADC. The default is Offset Binary, but Unipolar ("straight") Binary and Two's Complement are also selectable via jumpers W32-W39 on most models. (These are scattered all over the board; see your owner's manual.)
If you set the unipolar jumpers and use an R:Un parameter, Daqarta assumes straight binary coding has also been selected via W32-W39.
With bipolar ranges, most models allow Two's Complement coding instead of the default Offset Binary via these jumpers. There is no advantage to using this with Daqarta, but you may need it for compatibility with existing software. If you do this, add a 'T' before the range value, as in:
If you have also selected x2 ranges, you can combine this with the 'X', as in:
DT2821.ADC R:UT5The order of the U and T is unimportant.
Aside from the 'X', 'U', or 'T' letters, Daqarta tries to match any given range value with one of those in the following lists:
PGH models: PGL models: 10 10 5 5 2.5 1 1.25 0.5 0.625 0.1 0.05 0.02 0.01If an exact match is not found, Daqarta exits with:
'Invalid R: Range parameter.'You must, for example, use the leading zeroes exactly as shown. Note that when these same ranges are active in the Board menu, they may be displayed with a slightly different format and include a trailing "V" ("625 mV", for example)... don't use that here!
Certain R: parameter errors will cause Daqarta to exit with one of the following messages:
'R:Xn given, but specified Range is not x2.' 'Model does not support x2 Range jumper.' 'Specified R: Range not available on this Model.' 'Only 10V Range on this Model.'
S: CONVERSION SPEEDS, ADC and DAC:The S: parameter allows you to override the default ADC or DAC sample rates for your Model. The basic DT2821, for example, has a manufacturer's spec of 50 kHz maximum for the ADC and 130 kHz for the DACs. But on an actual board the ADC ran very well up to 80 kHz, and the DACs to 200 kHz.
To specify a different conversion speed, you must follow the S: parameter with a letter A for setting the ADC speed or a D for the DAC speed, followed by the minimum sample period in microseconds. For example,
DT2821.ADC S:A12 S:D5sets the ADC to 12 microseconds (83 kHz) and the DACs to 5 microseconds (200 kHz).
The minimum value you can set is 2 microseconds (500 kHz), and the maximum is 100 microseconds (10 kHz).
To determine the maximum ADC sample rate, start with a small period like S:A2. Use a known-good input waveform from any convenient source, such as a benchtop oscillator or function generator, or another system running Daqarta with an active STIM3 DAC or sound card Synth output. The frequency is not critical (1 kHz or so is fine), nor is the exact waveform (but triangle or sine is probably best... not square wave).
With the ADC sample rate at the start-up default of 20 kHz, adjust the input level to get a clean display of your input signal that is around half of full-scale. Now go to the X-axis control menu and raise the sample rate until you see the waveform begin to visibly distort, typically becoming noisy and spiky. Check both Sequential and RTime modes, and decide on a safe upper limit. Read the sample period directly from the menu item, and save this to use as your S:A value.
To find the maximum DAC rate, again start with a small period like S:D2. Feed one of the DAC outputs back to the ADC input. Bring up the STIM3 menu (CTRL-G) and activate that DAC. In Sequential mode, go to the Factor item and slowly raise it until you see visible distortion on the ADC trace. Ideally, you might also want to check this on an external oscilloscope, if one is available. But the ADC trace will typically show distortion sooner than the DAC output (due to slow CPU or ISA bus problems), so the ADC trace will probably be the limiting factor anyway.
Go to the X-axis menu and read the sample period directly, then divide by the Factor to get the S:D value. (Daqarta allows the DACs to run faster than the maximum ADC limits by means of its unique "hypersampling" operation.)
Repeat the test with both DACs active... you may find poorer performance. Now repeat the single-DAC and dual-DAC tests in RTime mode and you will typically find even poorer performance, especially on slow systems.
In RTime mode if you adjust the sample rate to get the fastest setting that just eliminates problems, you may find that spikes still appear on each keystroke unless you slow the sample rate even more. You may want to avoid operating in this "twitchy" range for normal work, but it can be used if you are aware of the limitations and don't use any keystrokes during averaging or DDisk recording, for example.
Decide where to set the ADC and DAC limits, based upon your own needs. For example, if you will be the only user and will run mostly in Sequential mode where higher sample rates can be achieved, you can base your S: settings on those values. Or you may want to set more conservative values to "bullet-proof" the system for less-knowledgeable users.
EXTERNAL PACER PRESET:The DT2821 allows an external TTL source (on pin 50) to be used instead of the internal sample rate pacer clock. You can toggle this mode on and off during operation using the Pacer control in the driver's Board menu. As an alternative, you can force this mode with the S:En option. This tells Daqarta to use the external clock input ONLY, and disables the Pacer control. The X-axis will also reflect the sample period implied by the S:En value.
A typical use would be:
DT2821.ADC S:E5In this example, the E5 indicates an external pacer with a sample period of 5 microseconds, or 200 kHz. This may be much faster than the actual sample rate, but it has the advantage that the frequency axis indicates 0 to 100 kHz, which you can interpret as 0 to 100% of the spectrum.
You can set any integer value from 2 to 65535 here. If your pacer signal is constant, or nearly so, you can just use the closest integer microsecond approximation of its period. If it varies all over the place, you may be better off with a 0 to 100% representation.
For analyzing rotating machinery, sample pulses are typically derived from a magnetic or optical pickup that monitors the passing teeth of a gear. If you want the X-axis to read directly in multiples of the main shaft speed (harmonic numbers), you need to do a little planning.
For example, suppose you put the pickup on a gear with 100 teeth, and that gear is driven 4 times faster than the main shaft. Then the pickup produces pulses 400x faster than the main shaft revolves. If you want the main shaft frequency (fundamental) to show as 1 Hz, you must indicate that the sample rate is 400 Hz (2500 microseconds) via S:E2500. The X-axis will then show 0 to 200 Hz, which you can interpret as 0 to the 200th harmonic.
Note that when you use the S:En option instead of the Pacer control, the sample period and frequency items in the X-axis menu will not be adjustable. If you use the Pacer control instead of S:En, you can change these items (and hence the frequency axis displayed), but either way the true sample rate is determined only by the external clock input on pin 50.
Additional discussion of external pacer operation is provided under the Pacer control topic.
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