Configuring Channels

Use the Channels tab on the Configuration Panel to activate and configure the analog, digital, and counter I/O channels to include in the acquisition. The settings that display are specific to the device selected on the Device Panel.

Channel settings are stored in a .amicfg file when you save the configuration.

Note: When running concurrent input and/or output operations with DAQami – whether among multiple devices or on a single device – there may be time lags between the data being acquired and/or generated for each operation. Although every effort is made to coordinate data timing between subsystems and devices, because all except one susbsystem is started through software, the virtual nature of the trigger for starting each operation results in some variation, particularly in the starting time.

When running composite I/O operations with DAQami using USB-1808 Series or USB-CTR Series devices, all susbsystem operations are synchronized by sharing a single hardware clock.

Note: When continuously acquiring more than 1 million samples per channel, you may experience performance issues depending on the PC that is running DAQami, the number of channels being sampled, the sample rate, and other factors. For optimal performance in this scenario, reduce the sample rate, reduce the number of active channels, and/or install a faster hard drive.

Tip: When selecting channels on this tab, press <Shift> to select multiple contiguous channels at the same time, or <Ctrl> to select and configure multiple non-contiguous channels. To select all channels, click anywhere in the grid and press <Ctrl-A>. The settings selected for one channel are applied to all selected active channels.

Click on the links below to go to the configuration procedure for each channel type:

Configuring Analog Input Channels

Complete the following steps to configure analog input settings:

  1. Select the Active checkbox for each analog input channel that you want to activate. The settings for each activated channel become enabled.
  2. To change the channel color, click the color swatch to open a color palette and select a color. The selected color is applied to the channel icon and data trace on displays.
  3. To change the channel name, double-click in the Channels column and enter the new name.
  4. If the device supports multiple measurement types, click the down arrow in the Type list and select the measurement type for the channel.
  5. The next available channel setting depends on the Type setting:
  6. Note: When acquiring data from a USB-2408 Series or USB-2416 Series device, click the down arrow on the Data Rate list to select a data rate for the acquisition. The maximum sample rate depends upon the data rate set for the channel(s) in the acquisition, and also controls noise filtering on each channel. Refer to the Setting the data rate to control noise filtering discussion below for more information.
  7. Select the Units to use for the acquisition.

    If you select Custom, complete the following steps to create a custom unit:
    1. In the Multiplier textbox, enter the value to use to scale data and to calculate the y-axis range. The default is 1.
    2. In the Offset textbox, enter a value to offset the data. The default is 0.

Analog input settings

Analog Input Settings
Color swatchThe color applied to the channel icon and channel data on a display. Click to open a color palette and select a color.
ChannelsThe name of each channel on the device. The name is included on each display to which you add the channel. You can enter a new name of up to 25 characters.
ActiveThe checkbox used to activate/deactivate a channel. Select the checkbox for each channel to include in the acquisition. Activated channels are listed on the Device Panel, and active input channel data is logged. Active channels can be added to displays.
TypeThe analog measurement type(s) supported by the device.
RangeThe range(s) supported by the device. This column is enabled when Type is set to Voltage.
TC TypeThe TC types supported by the device. This column is enabled when Type is set to Temperature; it is only visible if the device supports temperature measurements.
Channel ModeIf the selected device supports configuring some channels as single-ended and some as differential, select the mode for the selected channel. The default mode is Differential.
Data RateUSB-2408 Series and USB-2416 Series only. When acquiring data with a USB-2408 Series or USB-2416 Series device, the data rate controls the amount of noise filtering on each channel. By reducing the data rate, the averaging of samples increases, and noise drops correspondingly. If low noise is your main concern, select very low data rates starting at 2.5 Hz. At low rates, much of the noise is averaged out of the data, and issues such as reference noise become less important. Refer to the Setting the data rate to control noise filtering discussion below for more information.
UnitsThe unit used to convert the data. Selectable values are specific to the measurement type. Select Custom to create a unit not available on the list.

The unit is shown in parentheses after the channel name below the Active Channels list on the Device Panel.
MultiplierThe value used to scale data and to calculate the y-axis upper and lower range. This column is enabled when Units is set to Custom.
OffsetThe value used to offset each data point. This column is enabled when Units is set to Custom.

Configuring Analog Output Channels

Complete the following steps to configure analog output settings:

  1. Select the Active checkbox for each analog output channel that you want to activate. The settings for each activated channel become enabled.
  2. To change the channel color, click the color swatch to open a color palette and select a color. The selected color is applied to the channel icon and data trace on displays.
  3. To change the channel name, double-click in the Channels column and enter the new name.

Analog output settings

Analog Output Settings
Color swatchThe color applied to the channel icon and channel data on a display. Click to open a color palette and select a color.
ChannelsThe name of each channel on the device. The name is included on each display to which you add the channel. You can enter a new name of up to 25 characters.
ActiveThe checkbox used to activate/deactivate a channel. Select the checkbox for each channel to include in the acquisition. Activated channels are listed on the Device Panel, and active channels can be added displays.

Output control: Adding analog output channels to the Output display lets you manipulate the output voltage during the acquisition. If the selected device supports output scanning, you can also modify waveform settings. Refer to the Output Channel Controls discussion for more information about the real-time controls available with analog output channels.

Configuring Digital I/O Channels

Typical digital settings are shown here. The settings which display are specific to the selected device, and may differ from this example.

Complete the following steps to configure digital I/O settings:

  1. Select the Active checkbox for each digital channel that you want to activate. The settings for each activated channel become enabled.
  2. To change the channel color (optional), click the color swatch to open a color palette and select a color. The selected color is applied to the channel icon and data trace on displays.
  3. To change the channel name (optional), double-click in the Channels column and enter the new name.
  4. If the digital bit is configurable, click the down arrow in the Direction column and set the direction to either Input or Output.
  5. When a port is bit-configurable, the digital bits will run faster when all the bits are configured for the same direction.
  6. TC-32 users: The digital bits on PortB are used only to monitor alarm outputs, and cannot be used to acquire data. Refer to the hardware user manual for more information about the TC-32 digital bits.

DIO settings

Digital I/O Settings
Color swatchThe color applied to the channel icon and channel data on a display. Click to open a color palette and select a color.
ChannelsThe name of each channel on the device. The name is included on each display to which you add the channel. You can enter a new name of up to 25 characters.
ActiveThe checkbox used to activate/deactivate a channel. Select the checkbox for each channel to include in the acquisition. Activated channels are listed on the Device Panel, and active input channel data is logged. Active channels can be added to displays.
DirectionWhen the bit direction is configurable, select Input or Output.

Output control: Adding digital output channels to the Output display lets you manipulate the direction during the acquisition. If the selected device supports output scanning, you can also modify the square wave frequency and duty cycle. Refer to the Output Channel Controls discussion for more information about the real-time controls available with digital output channels.

Configuring Counter Input Channels

Typical counter input settings are shown here. The settings which display are specific to the selected device, and may differ from this example.

Complete the following steps to configure counter input settings:

  1. Select the Active checkbox for each counter channel that you want to activate. The settings for each activated channel become enabled.
  2. To change the channel color (optional), click the color swatch to open a color palette and select a color. The selected color is applied to the channel icon and data trace on displays.
  3. To change the channel name (optional), double-click in the Channels column and enter the new name.
  4. The Mode value is populated with the selection in the Selected Channel Settings area.

Counter input settings

Configuring a Channel for Events Mode

Events mode settings are shown in the image above. To configure a channel for event counting – counting rising or falling edges – complete the following steps:

  1. Select Events from the Mode list.
  2. From the Count Direction list, select whether to count Up or Down from the Initial Count.
  3. If the device supports edge selection, from the Starting Edge list, select Rising to count rising edges, or Falling to count falling edges.
  4. Leave the Units set to count Ticks, or choose Custom and enter a value. When Custom is selected, Multiplier and Offset columns are shown.
    Multiplier and Offset values are used to scale counter data. The default multiplier is 1; the default offset is 0.
  5. Enter the Initial Count of the counter when counting Up or Down.
  6. Select the Recycle checkbox to enable recycle mode and restart counting when the counter reaches the Maximum value (when counting up) or the Minimum value (when counting down). Clear this checkbox to stop the counter (Non-recycle mode) when Maximum or Minimum is reached.
  7. Select the Clear on Read checkbox to clear the counter after each synchronous or asynchronous read. The value of the counter before it was cleared is latched and returned. The counter is typically cleared to zero, but depending on the counting mode, it may be cleared to the Minimum value.
  8. Select the Range Limit checkbox to enable the Maximum and Minimum boxes. Set these values to mimic limit switches in a mechanical counter. The behavior of the counter depends on the Count Direction and Recycle settings:
    Count DirectionRecycle CheckboxCounter Behavior
    UpSelectedWhen the count reaches the Maximum value, the counter rolls over to the Minimum value.
    UpClearWhen the count reaches the Maximum value, the counter stops.
    DownSelectedWhen the count reaches the Minimum value, the counter rolls over to the Maximum value.
    DownClearWhen the count reaches the Minimum value, the counter stops.
  9. Counting resumes if the direction is reversed or if the counter is reloaded with a value between Maximum and Minimum.
  10. Select one of the following functions from the Gate Function list:
  11. If gating is enabled, select the Gate Invert checkbox to activate the gate on a low-level or falling-edge gate signal. By default, the gate is active on a high-level or rising-edge input signal.

Frequency Mode Settings

To configure a channel for frequency counting – counting cycles over a period of time – complete the following steps:

  1. Select Frequency from the Mode list.

Counter input settings

  1. If the device supports edge selection, from the Starting Edge list select Rising to count rising edges, or Falling to count falling edges.
  2. From the Units list, select Hz, kHz, or MHz.
  3. From the Gate Function list, select Disabled to disable gating on the channel, or Gate Counter to enable gating on the channel.
  4. If gating is enabled, select the Gate Invert checkbox to activate the gate on a low-level gate signal. By default, the gate is active on a high-level input signal

Configuring a Channel for Period Counting Mode or Pulse Width Mode

To configure a channel for period counting – calculating the period of a cycle – or Pulse Width counting – measuring the time from the rising edge to the falling edge, or vice versa, on a counter input signal – complete the following steps:

  1. Select Period or Pulse Width from the Mode list. The settings below are the same for both modes.

Counter input settings

  1. If the device supports edge selection, from the Starting Edge list, select Rising to count rising edges, or Falling to count falling edges.
  2. From the Units list, select s (seconds), ms (milliseconds), µs (microseconds), or Ticks.
  3. From the Gate Function list, select Disabled to disable gating on the channel, or Gate Counter to enable gating on the channel.
  4. If gating is enabled, select the Gate Invert checkbox to activate the gate on a low-level gate signal. By default, the gate is active on a high-level input signal

Configuring a Channel for Timing Mode

To configure a channel for timing mode – calculating the time between an event on a counter input and a subsequent event on a counter gate – complete the following steps:

  1. Select Timing from the Mode list.

    Counter input settings

  2. If the device supports edge selection, from the Starting Edge list, select Rising to count rising edges, or Falling to count falling edges.
  3. From the Units list, select s (seconds), ms (milliseconds), µs (microseconds), or Ticks.
  4. If gating is enabled, select the Gate Invert checkbox to invert the Starting Edge setting.
Counter Input Settings
Color swatchThe color applied to the channel icon and channel data on a display. Click to open a color palette and select a color.
ChannelsThe name of each channel on the device. The name is included on each display to which you add the channel. You can enter a new name of up to 25 characters.
ActiveThe checkbox used to activate/deactivate a channel. Select the checkbox for each channel to include in the acquisition. Activated channels are listed on the Device Panel, and active input channel data is logged. Active channels can be added to displays.
ModeThe counter mode. The following counter modes are supported (depending on the counter functionality of the device):
  • Event—Counts rising or falling edges.
  • Frequency—Counts cycles over a specified period of time.
  • Period—Measures the period of a cycle.
  • Pulse—Measures the time from the rising edge to the falling edge, or vice versa, on a counter input signal.
  • Timing—Measures the time between an event on a counter input and a subsequent event on a counter gate.
Count DirectionWhen the selected Mode is Events, select Up to count up from Initial count, or Down to count down from Initial count
Starting EdgeThe edge to count; select Rising to count rising edges, or Falling to count falling edges.
UnitsThe unit used to convert the data. Selectable values are specific to the selected Mode. A custom unit can also be entered for each mode.
Initial CountThe starting value when counting up or down.
RecycleEnables the counter to restart counting when a specified value is reached.
Clear on ReadClears the counter after each read.
Range LimitMinimum and maximum values to read.
Gate Function:Enables a specific input to gate the counter. Selectable values are specific to the selected Mode.
Gate Invert:Enables the counter to increment upon an active low/falling edge/gate low signal.

Configuring Counter/Timer Output Channels

Typical counter output settings are shown here.

Complete the following steps to configure counter output settings:

  1. Select the Active checkbox for each counter output channel that you want to activate. The settings for each activated channel become enabled.
  2. To change the channel color, click the color swatch to open a color palette and select a color. The selected color is applied to the channel icon and data trace on displays.
  3. To change the channel name, double-click in the Channels column and enter the new name.

Counter input settings

Counter/Timer Output settings
Color swatchThe color applied to the channel icon and channel data on a display. Click to open a color palette and select a color.
ChannelsThe name of each channel on the device. The name is included on each display to which you add the channel. You can enter a new name of up to 25 characters.
ActiveThe checkbox used to activate/deactivate a channel. Select the checkbox for each channel to include in the acquisition. Activated channels are listed on the Device Panel, and active channels can be added to displays.

Output control: Adding counter output channels to the Output display lets you set frequency and duty cycle of the output. Refer to the Output Channel Controls discussion for more information about the real-time controls available with digital output channels.

Setting the data rate to control noise filtering (USB-2408 Series and USB-2416 Series only)

The data rate controls the amount of the noise filtering on each channel in a DAQami acquisition. By reducing the data rate, the averaging of samples increases, and noise drops correspondingly.

If low noise is your main concern, select a very low data rates starting from 2.5 Hz. At low rates, much of the noise is averaged out of the data, and issues such as reference noise become less important.

At higher data rates, higher-frequency noise sources are not averaged out and can begin to be problematic. These noise sources include the noise inherent in the A/D converter itself, which is not reducible. Since TCs can pick up noise in your environment, select a data rate based on the primary noise frequency.

For example, to reduce the effect of 60 Hz noise, select a data rate of 60 Hz (or a supported multiple of 60, such as 10 Hz or 5 Hz).

When acquiring from multiple channels, the sample rate is the same for all channels, but channels with a lower data rate have more filtering, or averaging, performed on the data.

For example, if you set a 10 Hz data rate for channel 0, and a 50 Hz data rate for channel 1, both channels pass the same number of samples per second to the host computer. However, more averaging is performed on channel 0 samples; therefore, channel 0 is sampled at a higher resolution.

The A/D converter on USB-2408 Series and USB-2416 Series devices perform averaging, and the number of averages equals 30,000/data rate. In this example, channel 0 is sampled 3000 times over 100 ms, and all samples are averaged into one sample. Then, channel 1 is sampled 600 times over 20 ms, and samples are likewise averaged into one sample. The final samples are available to you at a maximum rate of about 8 Hz (8.245 Hz).

See Also

Configuring Acquisition Settings

Configuring a Device

Saving a Configuration File

USB-2408 Series

USB-2416 Series