Author: burkard

# Galvani manual

- Start
- Menu
- Toolbar
- Settings
- Performing measurements
- Data evaluation
- Files and folders

## Settings

Settings for measurement and data plotting can be defined in the menu "Settings".
If the option "autoload options" is active, all parameters are read from the configuration file at program start.
If the option "autosave options" is active, all parameters are saved in the configuration file at program end.
Function parameters, which are defined in project or data channel settings, will be overwritten during the measurement, if the device is sending these data. Galvani options can be classified as:

- Project settings
- Diagram settings
- Settings for data channels

Project settings

In the project settings the main measurement parameters are defined:

- Title: A short identifier of the measurment project (optional).
- The function shown on x-axis (data channel 1).
- The function shown on y-axis (data channel 2).
- A project comment. In this entry the measurement parameters or a description of the sample can be filled in (optional).

For both channels these measurement functions ca be selected:

- DC voltage (default)
- DC current
- AC voltage
- AC current
- Resistance
- Electrical conductivity
- pH
- Temperature

In channel 1 (x-axis) the time variable can also be selected - this is the default option.
Galvani selects the unit (volt, ampere, ohm, siemens, pH, °C) according to the defined function. If the data sent by the device contain a function and a unit, project or channel settings are overwritten. Project settings are also overwritten when a simulation pH or spectrum is selected. With simulation spectrum the function wavelength (400-800 nm) is selected for x-axis and absorption (intensity) for y-axis.

Together with the measurement function the related device e.g. simulation type is shown. A click on this button leads to the settings menu where the related device can be configured.
For simulation of titration curves the convenient acid can be chosen from a dropdown list. The user can fill in the acid volume an concentration, the concentration of the titrator (sodium hydroxide) an the titration velocity. A value of 50 mL/min with a time interval of 0.1 seconds is suitable.
For the calculation of titration curves Galvani uses the tabulated pKs-values (H.R.Christen: Grundlagen der allgemeinen und anorganischen Chemie, Frankfurt a.M. 1980, G.H.Aylward, T.J.V.Findlay: Datensammlung Chemie, Weinheim 1975). The algorithm is based on the concept of de Levie (R. de Levie: "General expressions for acid-base titrations of arbitrary mixtures", Washington 1995 - Technical report #7, Chemistry Department, Georgetown).

Diagram settings

Diagram settings can be selected in menu Settings/diagram.

Background

A mouse click on the area opens a colour selection window where the background colour can be chosen.

Colour of axes

A mouse click on the area opens a colour selection window where the axes' colour can be chosen.

Grid

Turn on the switch to show the grid.
A mouse click on the area opens a colour selection window where the grid colour can be chosen.

Data points

To define the appearance and the junction of data points, these options can be chosen:

- Symbol (cross, circle, square, diamond or no symbol)
- Appearance of symbols (filled or outline)
- Size of the symbols in points
- Junction of symbols (line, curve or no junction).
  Galvani calculates curve segments by cubic (Hermite) splines.
- Line style (solid, dashed or dotted)
- Line colour: A mouse click on the area opens a colour selection window where the line colour can be chosen.

Scaling

Turn on the switch for autoscaling the diagram coordinates. Another switch forces the zero line to be shown.
The limits of the coordinate system can be adjusted manually in the appropiate entry fields. If the switch "autoscale" is on, the coordinate system is adjusted to actual data based on the manually defined.

Project title

Turn on the switch to show the project title as headline of the diagram.

Settings for data channels

Parameters for data channels can be selected in menu Settings/Data channel X / Y.
Most options are identical for both data channels. The time variable can only be selected for channel 1 (x-axis). Other devices than digital multimeters can be chosen only for channel 2 (y-axis).

Data source

The time variable is the default function for channel 1.
In addition there are the following options:

- Digital multimeter (default for channel 2)
- Other device (only channel 2)
- Simulation

Measurement interval

The measurement interval (the time difference between two measurements) can be chosen up to a maximum of 1 hour (3600 seconds). The minimum is defined by the multimeter or device (parameter "timeout").
Choose the measurement interval in the selection window for channel 2 (y).

Data source simulation

This option allows the simulation of measurements. Galvani modulates the calculation of data with random variables.
The following functions are available:

- Linear
- Exponential (decay curve)
- Chromatogram (Peak modeling by Gauß function)
- Spektrum (modeling of an absorption spectrum in the visible wavelength range of 400-800 nm by Lorentz function)
- pH-diagram (1 or 2 equivalence points and pKs values are assigned at random)

Data source digital multimeter

Galvani supports communication to the instrument over a serial (RS232C) or USB (USB-TMC) interface. In order to communicate to the device the user must have access to these interfaces.
A common way to achieve this for the serial interface is to add the user to the group dialout:
sudo usermod -aG dialout [username].
For an USB interface a file "usbtmc.rules" can be generated in /etc/udev/rules.d/:
# Devices
KERNEL=="usb/*", MODE="0660", GROUP="plugdev"
KERNEL=="usbtmc[0-9]*", MODE="0660", GROUP="plugdev"
In that way the interface is writable by the group plugdev. If necessary the user can be added to this group:
sudo usermod -aG plugdev [username].

Galvani supplies configuration files (extension .dmm) for some devices. They can be found in the user's Galvani data directory ~/galvani/. This version of Galvani supports only devices sending ASCII data. Galvani supports although communication by SCPI commands (Standard Commands for Programmable Instruments).
With the Load button the device settings are read from a configuration file and saved in a list of up to 10 devices. Configured devices can be selected for measurements on both channels.
Manually configured parameters can be saved as files by clicking on the Save button.

Parameters for serial communication:

- Interface: Galvani lists all available interfaces.
  The interfaces /dev/ttyS0 - /dev/ttyS3 are listed even when they are physically not available. When they are chosen in this case, this leads to a corrupted port, which cannot be resetted. The program then must be restarted.
  An interface is occupied by a measurement operation. It will be unavailable until the measurement process is terminated.
  When a serial interface (RS232C) is chosen, further parameters are shown (see below).
- SCPI (switch): The instrument supports communication by SCPI commands.
- Remote control (switch): The measurement function of the device can be set up over the serial interface.
  If this switch is on, measurement function and range can be selected in further choice boxes and input fields can be filled with control strings.
- Baudrate: data transfer rate (600-115200 Bit/s)
- Charsize: number of data bits (7 or 8)
- Stopbits: (1 or 2)
- Flowcontrol: control of serial communication (hardware, software or none)
- Parity: control bit (odd, even or none)
- Polling (switch): The device expects a request character ("D" or "MEAS?" in case of SCPI) before sending data.
- Bytes: Galvani waits for the specified number of bytes to be sent by the device (default: 0).
- Values: Number of data values sent by the device (default: 1)
- Timeout: Minimal timeout between data readings (device dependent).

Data source device

Besides digital multimeters other measuring devices with serial communication can be used in Galvani. The device being chosen only the interface must be selected.
This version of Galvani supports the following devices:

- pH meter Lutron PH-207