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Current Page: Start » CFD200 .NET API
|The CFD200 is a 2 channel multimeter / oscilloscope card for notebooks
and PocketPCs manufactured by ELAN Digital Systems Ltd.
Schilling Systeminformatik offers a .NET C# API for the CFD200. The CFD200 is
introduced in the following sections.
The CFD200 Compact-Flash DMM
The CFD200 turns the PocketPC into a 2 channel 5 digits DMM with
oscilloscope capability for not-too high frequencies. The display can
be switched to DMM or scope mode for each channel as shown on the
images below by simply tapping into the display area. Please note that
typical DSOs habe a physical resolution of 8 bit vertical - this DMM
has 24 bits with about 15 usable bits at the maximum sample rate. In
any case the resolution is much higher than the PocketPC display can
resolve by default.
A nice feature for hands free DMM operation is the voice reading that
can be actived in 15 or 30 seconds intervals or by changes in the
reading. In addition readings can be logged to a file with different
speeds.
As the screen indicates, the two DMMs work independent of each other
(except for the sample rate), so you can set different measurement
units for each DMM, i.e. measure volts with the first and amps with the
second DMM. This goes far beyond simple scanner cards!
In DMM mode the voice feature is replaced by a zooming feature that we
couldn't get working. You see it is grayed out.
The card uses a Sigma-Delta ADC providing up to 40.000 conversion per
second and channel. This kind of ADCs tend to low-pass filter the
incoming signal. For that reason the bandwith is limited to around 1kHz
in the 6V range and 6kHz in the 60V range. If you take a look at the
square wave in the scope display in the middle above you will find that
the edges are rounded indicating that the higher frequency parts of the
450Hz square wave have been attenuated.
The CFD200 provides these ranges:
- Auto DC / AC RMS
- 2V
DC: This range has a very high input resistance, for that reason the
readings vary if nothing is connected. This effect is known from other
DMMs like Keithleys K2001 that has 10GOhm input resistance. That's no
malfunction, if a voltage source is connected, the readings will
stabilize!
- 6V DC / AC RMS
- 60V DC / AC RMS
- 650V DC / AC RMS
- 350mA DC (Yes only one range, and no AC range!)
- 10kOhm: resolves down to 0.1Ohms, but even short
returns ~2.6Ohms. This is within the states accuracy of 10Ohms in this
range.
- 100kOhm: Resolves down to 1 Ohms.
- 10MOhm
- 40MOhms: This is the
10MOhm range with a shunt resistor in parallel. Using this method very
high resistances can be measures, but the accuracy suffers.
- Diode-Check: The result is in volts (forward bias
voltage of the diode), looks like the 10kOhm range with voltage reading.
- Short-Check: Result is in ohms, apperently identical
to 10kOhm range
Like a real oscilloscope there are settings for triggering. The default
setting is "Auto trigger on" giving immediate results without
complicated settings. The settings are pretty much self-explaining for
scope users.
Installation of the CFD200 Graphical application on the
PocketPC
Install CFD200_Graphical_PPCApp.exe
- in default location Main memory: Ok
- in Built-in storage:
- After inserting CFD200, driver is
asked for:
cfd200_drvr
- Execute Graphical DMM Shortcut: "Not
found"
- in SD card: Same as built-in storage
-> Install the
application always
in the default "Main memory", you can move it later this way:
Moving CFD200_Graphical_PPCApp:
- Install first in default location.
- Using File Explorer, goto \Windows and cut the folder "CFD200".
- Paste it wherever it shall be located, i.e. "Built-in Storage"
- Goto the new location, mark CFD200_Graphical_PPCApp.exe and select
"Copy".
- Goto Windows\Start Menu\Programs, scroll to the botton and select
"Paste Shortcut"
- For the logging feature works: Goto \Windows, select New folder and
create the directory "CFD200". In the new folder create the directory
"logs".
CFD200 with PocketPC2003SE or Mobile 5
The operating system we used is Windows Mobile® 2003 Second
Edition
(standard on X50 devices). However there is an upgrade to Windows
Mobile® 5.
We checked the upgrade in December 2006 with the current Dell "A02 ROM
version" and with the first "A01 ROM version".
To say short: Using this PDA the card does not work with Windows
Mobile® 5. It is
not recognized. There are problems in accessing CF cards in the "I/O
mode". This seems to be a problem of the operating system, some timings
need to be changed. If you want to know more, google for "IORD#" and
"PeteSleeman", there is some additional information in the Dell Support
forums.
We hope this issue will be resolved in future as this affects many
non-ATA CF cards.
We can confirm that the CFD200 works fine using Windows
Mobile® 5 in a TDS Recon 400 PDA.
Programmable features
Up to now the CFD200 has been compared to standard handheld DMMs. This
is a bit unfair, since the CFD200 is fully programmable! It comes with
an API so you can integrate it in whatever application
you may think of, but:
The API is much different from SCPI, is a low level function interface
that
provides full access to the card, but requires the user to understand
how the card works internally, taking care of sample rate, setup and so
on. This is especially true for the AC ranges. The user must take care
of sample rates, averaging, converting the result and so on. Don't
think of it that you simply set the range and get an accurate result,
it's more like a data acquisition card with DMM ranges.
CFD200 .NET API
For that reason we offer an add-on for the basic CFD200 driver. It is
an API for .NET / C# using PocketPC 2003SE or Windows Mobile 5. It comes
with an example application and an enhanced class that simplifies using
the DMM. Just set the range and get a result.
The API is available at our distributors.
Summary
The
CFD200 will surely not replace standard DMMs - the combination of
standard PDA and CF card is too expensive and not as rugged as a
typical DMM. On batteries it won't last a day (although additional
Li-Ion batteries are cheap, small and lightweight), and imagine it gets
lost - very expensive.
Second its drawbacks in the measurement of low resistances, the missing AC
current range and only one DC current range limit its usage.
But if you need a
compact combination of PDA and DMM, we
don't know of an alternative!
To summarize:
- 5 digit DMM with
2 channels
- Data logger with virtually infinite capacity. Try to fill a 2 GB
SD-card with data...
- Low frequency oscilloscope
- Fits into
(bigger) pockets or executive cases.
- Replaces two datalogging 5
digit DMMs and a low-end handheld DSO for the same purpose. These need
definitely much more space and the weight will be much higher.
- Weaknesses:
- Measurement of low resistances, minimum range only 10kOhms
- One DC current range, no AC current range
<- 50 years
of development
between these two instruments:
Hartmann und Braun Multavi II
(manufactured 1938 – 1960)
Dell Axim X50v + ELAN CFD200