Receives data from a multimeter Gossen METRAHit 29S via BD232 serial interface.
Tested with FTDI and similar RS232 USB serial interfaces to "/dev/ttyUSB0" (linux).
Should also work for Windows with e.g. serial_device="COM8".
Activate the transmission on the instrument with: 'SEt v SEnd <-/ OFF v on <-/', or at switch-on by depressing DATA/CLEAR and ON button together. Rate of data beeing sent can be set in the meter's menu with the item 'rAtE'.
Get info and documents from gossenmetrawatt.com.
Access to the multimeter and decoding of the received data is done in the OpenMetra class.
Just add the directory openmetra to your project and you're done.
Switch the meter to transmit mode (press DATA/CLEAR and ON together) and retrieve the data with this simple program:
#!/usr/bin/python
import sys
from openmetra import OpenMetra
with OpenMetra() as mh: # open connection to '/dev/ttyUSB0', the serial path can be an optional parameter
if mh is None: # could not connect
print( 'connect error', file=sys.stderr)
sys.exit()
while True: # run forever, stop with ^C
try:
print( mh.get_measurement() ) # print numeric value
except KeyboardInterrupt: # ^C pressed, stop measurement
print()
break # exitThe provided program Metra allows to customize the received date with some options:
usage: Metra [-h] [-c] [-d SERIAL_DEVICE] [-f] [-g] [-n NUMBER] [-o] [-O] [-r RATE]
[-s SECONDS] [-t] [-T TIMEOUT] [-u] [-U] [-v] [-V]
Get data from Gossen METRAHit 29S
optional arguments:
-h, --help show this help message and exit
-c, --csv create csv (together with -t and/or -u)
-d SERIAL_DEVICE, --device SERIAL_DEVICE
device path of serial interface, default is "/dev/ttyUSB0"
-f, --format_values print formatted values (instead of as shown on meter)
-g, --german use comma as decimal separator, semicolon as field separator
-n NUMBER, --number NUMBER
get NUMBER measurement values
-o, --on-off switch meter on, select send mode and rate and switch off after
measurement
-O, --overload print OL values as "None" instead of skipping
-r RATE, --rate RATE select index for measurement rate: 0:50ms, 1:0.1s, 2:0.2s, 3:0.5s,
4:1s, 5:2s, 6:5s, 7:10s, 8:20s, 9:30s, 10:1min, 11:2min, 12:5min,
13:10min, default: 4 (1s)
-s SECONDS, --seconds SECONDS
measure for a duration of SECONDS
-t, --timestamp print timestamp for each value
-T TIMEOUT, --timeout TIMEOUT
set timeout for serial port
-u, --unit print unit of measured value
-U, --unit_long print unit of measured value with explanation, e.g. AC, DC, etc
-v, --version show openmetra version
-V increase verbosity
The program MetraPlot displays the measured data nicely:
usage: MetraPlot [-h] [-t TITLE] [-f FIRST_SAMPLE] [-l LAST_SAMPLE] [-V] [infile]
Plot data - e.g. received from Gossen METRAHit 29S via program 'Metra'
positional arguments:
infile read measurement data from optional infile, use stdin otherwise
optional arguments:
-h, --help show this help message and exit
-t TITLE, --title TITLE
set the title of the plot, default is 'MetraPlot'
-f FIRST_SAMPLE, --first_sample FIRST_SAMPLE
first sample to display
-l LAST_SAMPLE, --last_sample LAST_SAMPLE
last sample to display
-V increase verbosity
The program MetraSwitch switches the instrument on and selects send mode or selects the measurement function or switches the intrument off:
usage: MetraSwitch [-h] [-d DEVICE] [--off | --function FUNCTION | --rate RATE | --set_rtc]
[-v] [-V]
Gossen METRAHit 29S: switch off or select function or select data rate or set RTC time and
date. Without specifying an action the meter is just switched on.
optional arguments:
-h, --help show this help message and exit
-d DEVICE, --device DEVICE
device path of serial interface, default is "/dev/ttyUSB0"
--off switch the device off
--function FUNCTION select measurement function: 1:V_DC, 2:V_ACDC, 3:V_AC, 4:mA_DC,
5:mA_ACDC, 6:A_DC, 7:A_ACDC, 8:Ohm, 9:F, 10:dB, 11:Hz_Uacdc,
12:Hz_Uac, 17:Ohm buzzer, 18:Temp, 22:pulseW, 23TRMS_mains,
24:Counter, 25:Events_Uacdc, 26:Events_Uac
--rate RATE select index of measurement rate: 0:50ms, 1:0.1s, 2:0.2s, 3:0.5s,
4:1s, 5:2s, 6:5s, 7:10s, 8:20s, 9:30s, 10:1min, 11:2min, 12:5min,
13:10min
--set_rtc set meter RTC time and date from local time
-v, --version show openmetra version
-V increase verbosity
The provided Makefile allows to build a Debian package,
just type make. make distclean removes all created data to prepare for a new clean build.
You need to install python3-stdeb, the Python to Debian source package conversion plugins for distutils.
After success the package is available as openmetra_*_all.deb.
You can do a clean install (as root) with dpkg -i openmetra_*_all.deb, the python module openmetra is put into
the python3 library path, the scripts Metra* are copied into /usr/bin. dpkg -P openhantek does a clean uninstall.
It is also possible to build an (experimental) rpm package with make rpm as openmetra-*.noarch.rpm.
The instrument sends the data blocks with 9600 Bd, 8 bits + Start + Stop bit (only lower 6 bits are used).
TM1a) Measured data with fast rate (rate 50 ms, V_DC, A_DC only)
-----------------------------------------------
|Byte| Output unit Bit0..Bit3 |Bit5|Bit4|
|----|------------------------------|----|----|
| 1 | Measuring range, sign | 0 | 1 |
| 2 | Units | 1 | 1 |
| 3 | Tens | 1 | 1 |
| 4 | Hundreds | 1 | 1 |
| 5 | Thousands | 1 | 1 |
| 6 | TenThousands | 1 | 1 |
-----------------------------------------------
TM1b) Instruments setting with fast rate (sent at lower rate of ~ 500 ms)
-----------------------------------------------
|Byte| Output unit Bit0..Bit3 |Bit5|Bit4|
|----|------------------------------|----|----|
| 1 | Device code, 1110 is 29s | 0 | 0 |
| 2 | Curr. type, meas. variable 1 | 1 | 1 |
| 3 | Special character 1 | 1 | 1 |
| 4 | Special character 2 | 1 | 1 |
| 5 | Measuring range, sign 1 | 1 | 1 |
-----------------------------------------------
TM2) Ranges: V AC, V AC+DC, I AC+DC, Ohm, Ohm with buzzer, F, Hz , Temp., dB, V-diode, V-diode with buzzer, Events, Counter, Mains analysis and Power. Also V DC, A DC and functions when send interval >50 ms.
-----------------------------------------------
|Byte| Output unit Bit0..Bit3 |Bit5|Bit4|
|----|------------------------------|----|----|
| 1 | Device code, 1110 is 29s | 0 | 0 |
| 2 | Curr. type, meas. variable 1 | 1 | 1 |
| 3 | Special character 1 | 1 | 1 |
| 4 | Special character 2 | 1 | 1 |
| 5 | Measuring range, sign | 1 | 1 |
| 6 | Units | 1 | 1 |
| 7 | Tens | 1 | 1 |
| 8 | Hundreds | 1 | 1 |
| 9 | Thousands | 1 | 1 |
| 10 | TenThousands | 1 | 1 |
| 11 | HundredThousands | 1 | 1 |
| 12 | Curr. type, meas. variable 2 | 1 | 1 |
| 13 | Send interval | 1 | 1 |
-----------------------------------------------
29S: In case of power measurement there are sent 3 of these blocks with delay 200 ms in order power - W, voltage - V, current - A.
The meter's function is transmitted in Current type measuring variable 1 (fast mode)
or Current type measuring variable 1 and Current type measuring variable 2 for slow mode.
Thes values were verified with my METRAHit 29s:
TM3b) Measurement function encoding (also TF)
-------------------------------------------------
| Function | Variable2 | Variable1 | Index |
|-----------+-----------+-----------+-----------|
| - | 0000 | 0000 | 0 |
| V DC | 0000 | 0001 | 1 |
| V ACDC | 0000 | 0010 | 2 |
| V AC | 0000 | 0011 | 3 |
| mA DC | 0000 | 0100 | 4 |
| mA ACDC | 0000 | 0101 | 5 |
| A DC | 0000 | 0110 | 6 |
| A ACDC | 0000 | 0111 | 7 |
|-----------+-----------+-----------+-----------|
| kOhm | 0000 | 1000 | 8 |
| Farad | 0000 | 1001 | 9 |
| dBV | 0000 | 1010 | 10 |
| Hz UACDC | 0000 | 1011 | 11 |
| Hz UAC | 0000 | 1100 | 12 |
| W (mA) | 0000 | 1101 | 13 |
| W (A) | 0000 | 1110 | 14 |
| Diode | 0000 | 1111 | 15 |
|-----------+-----------+-----------+-----------|
| Dio buzz | 0001 | 0000 | 16 |
| kOhm buzz | 0001 | 0001 | 17 |
| Temp | 0001 | 0010 | 18 |
| - | 0001 | 0011 | 19 |
| - | 0001 | 0100 | 20 |
| - | 0001 | 0101 | 21 |
| - | 0001 | 0110 | 22 |
| - | 0001 | 0111 | 23 |
|-----------+-----------+-----------+-----------|
| - | 0001 | 1000 | 24 |
| - | 0001 | 1001 | 25 |
| - | 0001 | 1010 | 26 |
| mA (W) | 0001 | 1011 | 27 |
| A (W) | 0001 | 1100 | 28 |
| V (W) | 0001 | 1101 | 29 |
| V DC | 0001 | 1110 | 30 |
| V DC | 0001 | 1111 | 31 |
-------------------------------------------------