DMMtr5 - a mobile datalogger
Measurements with a Digital MutiMeter
and a Psion 5 (5mx, MX-pro, MC218).
A) DMMtr5 - what this software does
The system METEX (or VOLTCRAFT) Digital Multimeter (DMMtr)
+ PSION5 + this software is characterised best as a small lightweight
data recording system for slowly varying processes - a datalogger!
Because of its low power consumption it is particularly suited for
observations in the field of processes which are slow, have long
(even years!) duration and for which electrically readable sensors
Here are 2 sample output screen dumps:
B) Feature list
C) Connecting a DMMtr
Connect the PSION 5 with the serial interface cable to the METEX M-3640D Digital Multimeter as follows:
VOLTCRAFT function DB-9
Pins 1 and 6 are connected to DTR, RTS is left unconnected. Wire wrap binding posts make a good plug for the meter.
All manipulations with the PSION and the multimeter are entirely at your own risk and responsibility!
This schematic works for the METEX M3640D DMMtr. If other digital
multimeters really collaborate with this software is unknown
to the author.
The link http://www.gerald-gradl.de/eprojects/multi/body_multi.html gives some additional info on how to make another plug. However, use care. Keep in mind that the Psion RS232 cable has NOT the standard signals on the D9 pins (null modem configuration).
The application is conveniently installed with a sis file.
On the PC: With PsiWin installed, just double click on the DMMtr5.sis file.
Alternatively, transfer the sis file to the Psion, then double tap on the file. While installing, select the drive where the application should be installed.
Select function: Select 'Demo' mode if you want to learn about this software. A cosine function of measuremet values is simulated. You do not need to connect a digital multimeter (DMMtr) to the serial interface.Select 'Measurement' and connect a DMMtr properly to the serial interface.
path for storing graphs and CSV: both file types will be stored in this folder. Use X:\foldername\abc\ (with a trailing \).
CSV data separator: select a character that should separate the data values in the CSV file. Use one of these characters: tab ; : ,
CSV decimal separator: use dot . or comma , like in your
Psion system, depending on your country. Numbers will appear as
1.5 or 1,5 . If you select the wrong one, you may not be able to
import these data into a Excel or spreadsheet.
The minimum delay between 2 measurements was found to be about 1.2 seconds. On Screen 1 you can select values for one time division between 2.4 seconds and 240 days. This allows a timerange between 26.4 seconds and 7.2 years per graph (on a Psion S5, which has 11 time units on the time axis). 1 to 99 graphs are allowed per measurement series.
If you need another setup of the time axis, select "individual". You will be asked for 2 parameters: spacing between 2 measurement in pixels, and the time delay between them.
G) Screen 1 parameters
maxrange: upper end of ordinate (y-axis)
minrange: lower end of ordinate (y-axis)
TimeUnit: time unit per division. A Series 5 screen has 11 time units on the time-axis
trigger/time axis: automatically or manually triggered with 'Enter' key. Automatic triggering can be done with absolute (system time of your machine) or relative time (starting with t=0).
number of screens: number of graphs and datafiles to complete. For long events, your measurements will be written on the desired number of consecutive screens - up to 99.
H) Screen 2 parameters
record data on csv: record time and data in an ASCII file in CSV style (=comma separated variables)
Threshold action: when the threshold values are exceeded, the machine can do long or short beeps to call your attention, or nil.
upper threshold value: Threshold action is executed when upper value is overrun.
lower threshold value: Threshold action is executed when lower value is underrun.
I) Graph properties
The graph is saved as a bitmap named DMMtrxxx.PIC where
xxx is the next available integer < 1000; the search always starts at 001. The file has a header of 20 bytes followed by 160 image lines of 60 bytes each. A set bit in each byte represents a black image pixel, a cleared bit represents a white pixel.
After viewing you may enter a comment that is written into the file on the content/meaning of the measurement.
Hint: use the fine graphic EPOC software MBMview from the late Lieuwe de Vries to print or manipulate the pic files.
J) CSV data files
If selected in Screen 2, the recorded data are stored in a csv style text file.
file name: DMMtrxxx.csv where xxx is the same number as in the corresponding graph filename DMMtrxxx.pic.
first record: Header string "CSV data file produced by D M M t r 5 - VX.XX" plus CR plus LF
second record: 126 byte long header string plus CR plus LF
subsequent records: max. 12 byte long string with time in seconds plus 'CSV data separator' plus 14 byte long string with measurement value plus 14 byte long string with integral-over-time value (measurement values summed up, measured as unit * hour) plus CR plus LF. For the terms 'CSV data separator' and 'CSV decimal separator' see "Settings".
Unit mapping: uF -> nF; uA -> mA; MOhm, Ohm -> kOHM; MHz -> kHz"
K) Data transfer to Psion's Sheet
... is easy if you select:
Open the CSV file with an editor, press Ctrl+A, then Ctrl+C to mark and copy all of the text, open Sheet and press Ctrl+V to paste the copied content. Then use sheet as usual.
L) Data transfer to Excel
... is easy if you select:
Transfer the file to the PC and double click on the csv file.
X) Supported digital multimeters
The DMMtr5 software should work with all multimeters with a RS232 interface of 1200 Baud, no parity, 7 data bits, 2 stop bits, and 14 bytes of data per measurement. The DMMtr must send the data after a "D" command is sent to it.
Unconfirmed list of multimeters:
Confirmed list of multimeters:
Does NOT work with:
Y) About this software
The software was written as freeware by Ulrich Hornstein, Freiburg, Germany, based on the program DMMtr for a Psion 3c from P.M.W. Navé
Downloads: 443 (since 17.11.2005)
Please include in your mail the model name of the multimeter that you intend to use. To complete the confirmed list of multimeters, I will expect a short feedback if your model collaborated with DMMtr5.
Information on this web site is provided "as is" without warranty of any
kind, either expressed or implied, including, but not limited to, the implied
warranties of merchantability, fitness for a particular purpose, or
non-infringement. Some jurisdictions do not allow the exclusion of implied
warranties, so the above exclusion may not apply to you.