Lawson Labs, Inc.
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800-321-5355 or 610-725-9344
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FAX 610-725-9344
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special notes for users of the EMF-16
Graphics Software for Win98/ME/NT/2k/XP
A) Basic Operation Instructions
1) Start software and select COM port for EMF16.
2) Click the SignOn button to establish communication. The "RUN"
LED on the EMF16 will light after successful initialization.
3) Click Start Scan to begin and Stop Scan to end.
B) Scan Set Up
1) Pick an internal data rate and remote averaging value. If you
are running long, slow tests, 10 Hz is the minimum rate. 10 Hz
will also provide the lowest noise. For faster response, we
recommend a 60 Hz internal data rate where the line frequency is
60 HZ, and a 50 Hz rate where the line frequency is 50 HZ.
2) Remote averaging will increase the filtering, but will slow the
scanning rate. To get the smoothest data with the smallest data
files, increase remote averaging to the largest value that will
allow you to scan fast enough. See #4 below for scan rate.
3) Click SETUP to change the selected active channels. The 16 input
channels for the standard EMF16 are shown in the column labeled "0"
on the left. The selected active channels must be in a continuous
sequence.
4)Scan types:
Normal scanning is a compromise between maximum speed and stability.
It is often preferred for electrochemistry applications.
Calibration scan adds two extra channels to each scan and
corrects for offset drift. You may want to use some local
averaging with a caibration scan to keep the offset correction
from adding marginally to the noise. The offset drift is expected
to be less than 100 microvolts per degree C, so this correction
may be unnecessary in many applications.
Single-channel scanning allows much higher scan rates on one channel at
a time. The maximum scan rate is normally much slower than the data rate.
In Single-channel scan mode the two rates are nearly the same. The scan
must be stopped before a different single channel can be selected.
5) The minimum achievable scan interval will be automatically selected.
If you wish to scan more slowly, enter the desired (larger) interval.
6) Click CLOSE to return to the graphics screen.
C) Graphics Set Up
1) Up to 16 Channels can be plotted at the same time on the single
set of axes.
2) Channels to plot can be selected from among the active sub-channels
for any particular input channel. For the standard EMF16, the "MAIN"
channel should always be set to 1.
3) Adding or removing a channel from the plot does not change the
scanning sequence or the data logging files. It does change the
Autoscaling. Left or right mouse buttons can be used when
changing channels to graph. The left button will select or de-select
intervening channels. The right button toggles only one channel at
a time.
4) You can set the plus and minus full scale values by directly typing
the voltage desired and pressing Enter, or use Autoscale. The horizontal
axis timebase can also be changed directly in the same fashion.
5) Click the Text/Graphic Screen button to toggle between the
two presentations.
D) Offsets
1) Each EMF16 channel has its own small offset associated. To
remove these offsets, begin a scan with all inputs active and
electrically shorted using the plugs provided. Put the ground
switch in the SAFE position. Best results will be obtained with
remote averaging set at 8 or above. After a few minutes, click
Save offsets. That will force all readings at that time to be
zero.
2) Thereafter, those offset corrections will be stored and used
each time you start your software. If you want to redo the
offsets, click Save Offsets again.
NOTICE: If you save offsets inadvertently, or with floating channels,
subsequent data may be drastically shifted.
3) To permanently remove all saved software offset corrections, click
Reset Offsets.
E) Other Functions
1) Check the LOG box to save data to disk. The Data files are placed in
the working directory and are named using the date and time. Click the
box again to stop the data logging. A new file is created for each
Start Scan. Checking and unchecking the Log box during a scan will
result in gaps in your log file. Note that the first column in the file
is the time stamp.
2) BAUD can normally be left at 9600. If serial errors occur, or
sign on is troublesome, switching to 4800 BAUD will likely fix it.
3) Gain can be set in powers of 2. The input range is cut in half
for each increase in gain. Normal gain is 1 for a range of +/- 5 volts.
A gain of 2 gives a range of +/- 2.5 volts, 4 gives +/- 1.25 volts, etc.
Scanning must be stopped in order to change the gain.
4) Local Average is a running average calculated in the host computer.
The average array is pre-loaded with the voltages from the first
scan. For large averaging values and/or wide scans, you may see a
message on your screen that indicates the arrays are being initialized.
The textual data on your screen, the graph, and the data files all
reflect the averaged values.
The EMF-16 hardware
Please browse the web to HERE for more information
OVERVIEW
The EMF16 is a high-resolution, high input impedance, data acquisition system
for electrochemistry applications. It connects to a PC serial port for presentation
and storage of EMF data. The bundled software is written by electrochemists for
electrochemistry. It allows up to 16 channels of data to be scanned and displayed,
and saved to the disk in real time.The EMF16 is built around our proven 24-bit A/D
system. The DC specifications are much better than those of most pH meters. Linearity
is 0.002% of full scale, input impedance is 10^13 ohms, reproducibility is better than
one part per million. BNC connectors are provided for the 16 buffered inputs and for
the buffered reference electrode. All inputs are protected against overvoltage. Three
measuring modes are selectable via a front-panel switch. Further flexibility is provided
through software configuration.
The EMF16 is supplied as a complete system including the interface box and Windows
software, serial cable, power supply and comprehensive manual. A Macintosh version is
also available.
