Channels

The IM7 always measures voltage and current from the selected potentiostat as its two primary channels. In addition, you can configure synchronous and asynchronous channels to capture extra signals alongside your main measurement.

Synchronous channels from a PAD4 card are sampled at the exact same moment as the primary voltage and current channels.

Asynchronous channels e.g. from a TEMP-U2 card are sampled in an interleaved pattern between synchronous sampling points, as illustrated in the timing diagram below.

@startuml

mode compact
skinparam defaultFontSize 20
skinparam defaultFontName Arial
skinparam backgroundColor transparent

clock "Sampling Clock" as clk with period 100
concise "Sampling Type" as C
hide time-axis

scale 3000 width

@clk*0
C is "All Synchron Channels"

@60
C is "Async Ch 1"

@90
C is {-}

@clk*1
C is "All Synchron Channels"

@160
C is {-}

@clk*2
C is "All Synchron Channels"

@260
C is "Async Ch 2"

@290
C is {-}

@clk*3
C is "All Synchron Channels"

@360
C is {-}

@clk*4
C is "All Synchron Channels"

@460
C is "Async Ch 1":

@490
C is {-}

@enduml

For more details on sampling rates, see the FAQ section: Sampling Rate vs Output Data Rate.

Synchronous - PAD4

The Synchronous Channels tab lists all available PAD4 channels, grouped by device. Each channel has the following settings:

Enabled - Check or uncheck the box to include or exclude a channel from your measurements.
Impedance Role - Defines whether the channel measures a voltage or current signal (used for impedance calculations during EIS).
Factor and Offset - Apply a linear scaling to the raw channel signal.

../../_images/hardware_settings_synchron_channels.png

When enabled, these channels are sampled simultaneously with the primary voltage and current channels during DC measurements.

During EIS measurements, the enabled channels are also used to calculate additional impedances relative to the main voltage or current channel, depending on the selected Impedance Role.

Asynchronous

Asynchronous channels record additional analog signals during DC measurements. They do not participate in impedance calculations, but during EIS measurements they are still sampled once at each frequency point.

Analog input channels are provided by expansion cards such as the TEMP-U2 card. To add a channel, click the add button and configure the following fields in the dialog:

Channel - Select the hardware input from the dropdown (e.g. a temperature or analog voltage input).
Dimension - Enter a unique signal name for the channel (e.g. “Temperature T1” or “pH Value”).
Unit - Specify the unit of the measured quantity (e.g. °C or V).
Polynomial - Define a polynomial to convert the raw signal into the desired physical value. The polynomial is specified as semicolon-separated coefficients, where the first value is the slope (gain) and the second is the offset.

../../_images/hardware_settings_asynchron_channels.png

The example below shows four configured channels from a TEMP-U2 card: two temperature inputs, one analog voltage input, and one pH sensor input.

../../_images/hardware_settings_asynchron_channels2.png

The temperature channels are already scaled to °C by the controller, so they only need a simple linear polynomial with a gain of 1 and no offset (displayed as x). The first analog voltage channel (A1) uses the same x polynomial and directly displays the voltage present at the A1 connector.

The second analog voltage channel (A2) is configured for a pH electrode with a nonlinear calibration. This sensor reads pH 7 at 0 V and follows a Nernst slope of −59.16 mV per pH unit, resulting in the polynomial -16.903x + 7 (i.e. 1 / −0.05916 ≈ −16.903 as the gain, with an offset of 7).