Constants
- Updated2023-02-21
- 8 minute(s) read
Constants help clearly define specific function parameter values. These constants are included in the niimaq.h header file.
The following table lists the constant name, the function to which the constant applies, and a general description.
Constant | Use With | Description |
---|---|---|
IMG_ACQUIRE_ALL | imgGetAttribute imgSetAttribute2 | Acquire all fields. |
IMG_ACQUIRE_EVEN | imgGetAttribute imgSetAttribute2 | Acquire only even fields. |
IMG_ACQUIRE_ODD | imgGetAttribute imgSetAttribute2 | Acquire only odd fields. |
IMG_AQ_DONE | imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgPulseCreate2 | Asserted at the end of an acquisition when the last piece of data has been transferred to memory. |
IMG_AQ_IN_PROGRESS | imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgPulseCreate2 | Asserted when the device initiates an acquisition either through a software- or hardware-triggered start. |
IMG_BAYER_PATTERN_GBGB_RGRG | imgBayerColorDecode | Specifies the following Bayer pattern: GBGB RGRG |
IMG_BAYER_PATTERN_GRGR_BGBG | imgBayerColorDecode | Specifies the following Bayer pattern: GRGR BGBG |
IMG_BAYER_PATTERN_BGBG_GRGR | imgBayerColorDecode | Specifies the following Bayer pattern: BGBG GRGR |
IMG_BAYER_PATTERN_RGRG_GBGB | imgBayerColorDecode | Specifies the following Bayer pattern: RGRG GBGB |
IMG_BUF_COMPLETE | imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgPulseCreate2 | Asserted when an image buffer has been transferred to memory and is available for image processing. |
IMG_BUFF_ACTUAL_HEIGHT | imgGetBufferElement | Returns the actual height in lines of a buffer acquired in VHA mode. |
IMG_BUFF_ADDRESS | imgGetBufferElement imgSetBufferElement2 | Specifies the buffer address portion of a buffer list element. |
IMG_BUFF_CHANNEL | imgGetBufferElement imgSetBufferElement2 | Specifies the channel from which to acquire an image. |
IMG_BUFF_COMMAND | imgGetBufferElement imgSetBufferElement2 | Specifies the command portion of a buffer list element. |
IMG_BUFF_SIZE | imgGetBufferElement imgSetBufferElement2 | Specifies the size portion of a buffer list element (the buffer size). Required for user-allocated buffers. |
IMG_BUFF_SKIPCOUNT | imgGetBufferElement imgSetBufferElement2 | Specifies the skip count portion of a buffer list element. |
IMG_CMD_LOOP | imgGetBufferElement imgSetBufferElement2 (with IMG_BUFF_COMMAND constant) | Specifies a buffer list command of LOOP. Used as the command for the last buffer element, this constant causes an acquisition to perform a continuous type of acquisition such as a ring. |
IMG_CMD_NEXT | imgGetBufferElement imgSetBufferElement2 (with IMG_BUFF_COMMAND constant) | Specifies a buffer list command of NEXT. This constant causes an acquisition to take place on the buffer and to proceed to the next buffer list element. |
IMG_CMD_STOP | imgGetBufferElement imgSetBufferElement2 (with IMG_BUFF_COMMAND constant) | Specifies a buffer list command of STOP. Used as the command for the last buffer element, this constant causes an acquisition to perform a one-shot acquisition such as a sequence. |
IMG_COLOR_CHROMA_ BANDWIDTH_HIGH | imgSetAttribute2 imgGetAttribute | Highest bandwidth (default). |
IMG_COLOR_CHROMA_ BANDWIDTH_LOW | imgSetAttribute2 imgGetAttribute | Lowest bandwidth. |
IMG_COLOR_CHROMA_ PROCESS_ALWAYS_OFF | imgSetAttribute2 imgGetAttribute | Use when you use a monochrome camera (default for CCIR or RS-170). |
IMG_COLOR_CHROMA_ PROCESS_ALWAYS_ON | imgSetAttribute2 imgGetAttribute | Use when you use a color camera (default for NTSC or PAL). |
IMG_COLOR_CHROMA_ PROCESS_AUTODETECT | imgSetAttribute2 imgGetAttribute | Use if the camera type (monochrome or color) is unknown. |
IMG_COLOR_COMB_1LINE | imgSetAttribute2 imgGetAttribute | Comb filtering using one delayed line. |
IMG_COLOR_COMB_2LINES | imgSetAttribute2 imgGetAttribute | Comb filtering using two delayed lines. |
IMG_COLOR_COMB_OFF | imgSetAttribute2 imgGetAttribute | Comb filter disabled (default in S-Video (Y/C) mode). |
IMG_COLOR_LUMA_ BANDWIDTH_FULL | imgSetAttribute2 imgGetAttribute | All filters, including decimation filter, are disabled. Default value in CCIR or RS-170 mode. |
IMG_COLOR_LUMA_ BANDWIDTH_HIGH | imgSetAttribute2 imgGetAttribute | Highest available bandwidth with decimation filter enabled. Default value for PAL or NTSC mode. |
IMG_COLOR_LUMA_ BANDWIDTH_LOW | imgSetAttribute2 imgGetAttribute | Decimation filter enabled, lowest bandwidth. |
IMG_COLOR_LUMA_ BANDWIDTH_MEDIUM | imgSetAttribute2 imgGetAttribute | Decimation filter enabled, medium bandwidth. |
IMG_COLOR_REP_BLUE8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Blue color output. |
IMG_COLOR_REP_GREEN8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Green color output. |
IMG_COLOR_REP_HSI32 | imgGetAttribute imgSetAttribute2 | A color image encoded in 32 bits–8 bits unused and 8 bits each for the Hue, Saturation, and Intensity planes. |
IMG_COLOR_REP_HSL32 | imgGetAttribute imgSetAttribute2 | A color image encoded in 32 bits–8 bits unused and 8 bits each for the Hue, Saturation, and Luminance planes. |
IMG_COLOR_REP_HUE16 | imgGetAttribute imgSetAttribute2 | Specifies 16-bit Hue color output. |
IMG_COLOR_REP_HUE8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Hue color output. |
IMG_COLOR_REP_INT16 | imgGetAttribute imgSetAttribute2 | Specifies 16-bit Intensity color output. |
IMG_COLOR_REP_INT8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Intensity color output. |
IMG_COLOR_REP_LUM16 | imgGetAttribute imgSetAttribute2 | Specifies 16-bit Luminance color output. |
IMG_COLOR_REP_LUM8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Luminance color output. |
IMG_COLOR_REP_RED8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Red color output. |
IMG_COLOR_REP_RGB16 | imgGetAttribute imgSetAttribute2 | Specifies 16-bit RGB color output. |
IMG_COLOR_REP_RGB24 | imgGetAttribute imgSetAttribute2 | Specifies 24-bit RGB color output (default). |
IMG_COLOR_REP_RGB32 | imgGetAttribute imgSetAttribute2 | Specifies 32-bit RGB color output. |
IMG_COLOR_REP_RGB48 | imgGetAttribute imgSetAttribute2 | Specifies 48-bit RGB color output. |
IMG_COLOR_REP_SAT16 | imgGetAttribute imgSetAttribute2 | Specifies 16-bit Saturation color output. |
IMG_COLOR_REP_SAT8 | imgGetAttribute imgSetAttribute2 | Specifies 8-bit Saturation color output. |
IMG_COLOR_RGB_CORING_ LEVEL_NOCORING | imgSetAttribute2 imgGetAttribute | Coring function is disabled. |
IMG_COLOR_RGB_CORING_ LEVEL_C1 | imgSetAttribute2 imgGetAttribute | Coring activated for saturation equal or below 1 LSB. |
IMG_COLOR_RGB_CORING_ LEVEL_C3 | imgSetAttribute2 imgGetAttribute | Coring activated for saturation equal or below 3 LSB. |
IMG_COLOR_RGB_CORING_ LEVEL_C7 | imgSetAttribute2 imgGetAttribute | Coring activated for saturation equal or below 7 LSB. |
IMG_CURRENT_BUFFER | imgSessionExamineBuffer2 | Specifies to examine current buffer in a live acquisition. Waits until vertical blank to return the buffer to you. |
IMG_DEVICE_FRAME | imgCreateBuffer | Specifies the new buffer is created in onboard memory (not supported on the NI PCI/PXI-1407, NI PCIe-1427, NI PCIe-1429, NI PCIe-1430, NI PCIe-1433, or NI PXIe-1435 devices). |
IMG_FIELD_EVEN | imgGetAttribute imgSetAttribute2 | Specifies the start field of the acquisition as even. |
IMG_FIELD_MODE | imgGetAttribute imgSetAttribute2 | Specifies the acquisition mode as field. |
IMG_FIELD_ODD | imgGetAttribute imgSetAttribute2 | Specifies the start field of the acquisition as odd. |
IMG_FILTER_NONE | imgGetAttribute imgSetAttribute2 | Specifies no video filter. |
IMG_FILTER_NTSC | imgGetAttribute imgSetAttribute2 | Specifies the video filter is NTSC. |
IMG_FILTER_PAL | imgGetAttribute imgSetAttribute2 | Specifies the video filter is PAL. |
IMG_FRAME_DONE | imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgPulseCreate2 | Asserted at the end of acquisition into each image buffer. |
IMG_FRAME_MODE | imgGetAttribute imgSetAttribute2 | Specifies the acquisition mode as interlaced. |
IMG_FRAME_START | imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgPulseCreate2 | Asserted at the start of acquisition into each image buffer. |
IMG_FRAME_VALID | imgPulseCreate2 | Asserted while a frame is being transferred. |
IMG_FRAMETIME_10MINUTES | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 10 min. |
IMG_FRAMETIME_10SECONDS | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 10 s. |
IMG_FRAMETIME_1MINUTE | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 1 min. |
IMG_FRAMETIME_1SECOND | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 1 s. |
IMG_FRAMETIME_2MINUTES | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 2 min. |
IMG_FRAMETIME_2SECONDS | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 2 s. |
IMG_FRAMETIME_5MINUTES | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 5 min. |
IMG_FRAMETIME_5SECONDS | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 5 s. |
IMG_FRAMETIME_STANDARD | imgGetAttribute imgSetAttribute2 | Specifies a frame timeout value of 100 ms. |
IMG_GAIN_0DB | imgGetAttribute imgSetAttribute2 | Specifies the gain is +0 dB. |
IMG_GAIN_3DB | imgGetAttribute imgSetAttribute2 | Specifies the gain is +3 dB. |
IMG_GAIN_6DB | imgGetAttribute imgSetAttribute2 | Specifies the gain is +6 dB. |
IMG_HOST_FRAME | imgCreateBuffer | Specifies the new buffer is created in the host computer memory. |
IMG_IMMEDIATE | imgPulseCreate2 | Causes the function to generate a pulse when the function is executed. |
IMG_LAST_BUFFER | imgSessionExamineBuffer2 | Specifies to examine the last valid buffer in a live acquisition. |
IMG_LINE_VALID | imgPulseCreate2 | Asserted while a line of a frame is being transferred. |
IMG_LUT_BINARY | imgGetAttribute imgSetAttribute2 | Specifies a binary LUT, which converts the sampled data to a binary image of black and white. |
IMG_LUT_INVERSE | imgGetAttribute imgSetAttribute2 | Specifies an inverse LUT, which inverts the gray levels. |
IMG_LUT_INVERSE_BINARY | imgGetAttribute imgSetAttribute2 | Specifies an inverse binary LUT, which converts the sampled data into a binary image of white and black. |
IMG_LUT_INVERSE_LOG | imgGetAttribute imgSetAttribute2 | Specifies an inverse log LUT, which converts the sampled data to a logarithmic form that produces greater contrast in the white region. |
IMG_LUT_LOG | imgGetAttribute imgSetAttribute2 | Specifies a log LUT, which converts the sampled data to a logarithmic form that produces greater contrast in the black region. |
IMG_LUT_NORMAL | imgGetAttribute imgSetAttribute2 | Specifies a normal LUT. |
IMG_LUT_TYPE_DEFAULT | imgSessionSetUserLUT8bits imgSessionSetUserLUT16bits | Default LUT used to initialize all LUTs. |
IMG_LUT_TYPE_RED | imgSessionSetUserLUT8bits | Red channel LUT for RGB digital cameras or the PCI/PXI-1411. |
IMG_LUT_TYPE_GREEN | imgSessionSetUserLUT8bits | Green channel LUT for RGB digital cameras or the PCI/PXI-1411. |
IMG_LUT_TYPE_BLUE | imgSessionSetUserLUT8bits | Blue channel LUT for RGB digital cameras or the PCI/PXI-1411. |
IMG_LUT_TYPE_TAP0 | imgSessionSetUserLUT8bits imgSessionSetUserLUT16bits | Tap 0 LUT for digital devices. |
IMG_LUT_TYPE_TAP1 | imgSessionSetUserLUT8bits imgSessionSetUserLUT16bits | Tap 1 LUT for digital devices. |
IMG_LUT_TYPE_TAP2 | imgSessionSetUserLUT8bits | Tap 2 LUT for digital devices. |
IMG_LUT_TYPE_TAP3 | imgSessionSetUserLUT8bits | Tap 3 LUT for digital devices. |
IMG_OVERWRITE_GET_OLDEST | imgSessionCopyBufferByNumber imgSessionCopyAreaByNumber | Retrieves the oldest image in the buffer list if requested image has been overwritten. |
IMG_OVERWRITE_GET_NEXT_ITERATION | imgSessionCopyBufferByNumber imgSessionCopyAreaByNumber | Provides the next image with the corresponding index in the buffer list if requested image has been overwritten. |
IMG_OVERWRITE_FAIL | imgSessionCopyBufferByNumber imgSessionCopyAreaByNumber | Fails if requested image has been overwritten. |
IMG_OVERWRITE_GET_NEWEST | imgSessionCopyBufferByNumber imgSessionCopyAreaByNumber | Retrieves the most recently acquired image in the buffer list if requested image has been overwritten. |
IMG_POCL_UNKNOWN |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry is in an unknown state. |
IMG_POCL_NOT_SUPPORTED |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry does not exist on the device. |
IMG_POCL_NO_AUX_POWER |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry has no power supply and thus cannot provide power. |
IMG_POCL_BAD_FUSE |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry has a blown fuse and thus cannot provide power. |
IMG_POCL_DISABLED |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry is disabled. |
IMG_POCL_FAULT |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry has detected a fault. |
IMG_POCL_INITIALIZING |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry is initializing. |
IMG_POCL_INACTIVE |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry is enabled but not providing power. |
IMG_POCL_ACTIVE |
imgGetAttribute imgSetAttribute2 |
The PoCL circuitry is enabled and providing power. |
IMG_PULSE_POLAR_ACTIVEH | imgPulseCreate | Specifies the polarity of a pulse as active high. |
IMG_PULSE_POLAR_ACTIVEL | imgPulseCreate | Specifies the polarity of a pulse as active low. |
IMG_ROI_FIT_LARGER | imgSessionFitROI | Fits the specified ROI to the next largest alignment. If the ROI is already properly aligned, this value has no effect on the ROI. |
IMG_ROI_FIT_SMALLER | imgSessionFitROI | Fits the specified ROI to the next smallest alignment. If the ROI is already properly aligned, this value has no effect on the ROI. |
IMG_SCALE_DIV2 | imgGetAttribute imgSetAttribute2 | The vertical resolution is scaled down by a factor of 2. |
IMG_SCALE_DIV4 | imgGetAttribute imgSetAttribute2 | The vertical resolution is scaled down by a factor of 4. |
IMG_SCALE_DIV8 | imgGetAttribute imgSetAttribute2 | The vertical resolution is scaled down by a factor of 8. |
IMG_SCALE_NONE | imgGetAttribute imgSetAttribute2 | Performs no scaling. |
IMG_SIGNAL_EXTERNAL | imgPulseCreate2 imgSessionLineTrigSource2 imgSessionTriggerConfigure2 imgSessionTriggerDrive2 imgSessionTriggerRead2 imgSessionTriggerRoute2 imgSessionWaitSignal2 imgSessionWaitSignalAsync3 | Specifies the signal type as the external trigger lines. |
IMG_SIGNAL_ISO_IN | imgPulseCreate2 imgSessionLineTrigSource2 imgSessionTriggerConfigure2 imgSessionTriggerRead2 imgSessionTriggerRoute2 imgSessionWaitSignal2 imgSessionWaitSignalAsync3 | Specifies the signal type as the isolated input trigger lines. |
IMG_SIGNAL_ISO_OUT | imgPulseCreate2 imgSessionLineTrigSource2 imgSessionTriggerConfigure2 imgSessionTriggerDrive2 imgSessionTriggerRead2 imgSessionTriggerRoute2 imgSessionWaitSignal2 imgSessionWaitSignalAsync3 | Specifies the signal type as the isolated output trigger lines. |
IMG_SIGNAL_NONE | imgSessionTriggerRoute2 | Used to disable the route. |
IMG_SIGNAL_RTSI | imgPulseCreate2 imgSessionLineTrigSource2 imgSessionTriggerConfigure2 imgSessionTriggerDrive2 imgSessionTriggerRead2 imgSessionTriggerRoute2 imgSessionWaitSignal2 imgSessionWaitSignalAsync3 | Specifies the signal type as the RTSI trigger lines. |
IMG_SIGNAL_SCALED_ENCODER | imgSessionLineTrigSource2 | Specifies the signal type as the scaled encoder signal. |
IMG_SIGNAL_STATUS | imgPulseCreate2 imgSessionWaitSignal2 imgSessionWaitSignalAsync3 | Specifies the signal type as one of the status signals, IMG_AQ_DONE, IMG_AQ_IN_PROGRESS, IMG_BUF_COMPLETE, IMG_FRAME_DONE, IMG_FRAME_START, IMG_IMMEDIATE. |
IMG_TIMEOUT_INFINITE | imgSessionWaitSignal imgSessionWaitSignal2 imgSessionWaitSignalAsync3 imgSessionSerialRead imgSessionSerialReadBytes imgSessionSerialWrite imgSessionTriggerConfigure imgSessionTriggerConfigure2 (with IMG_ATTR_FRAMEWAIT_MSEC constant) |
Used to wait indefinitely. |
IMG_TRIG_ACTION_BUFFER | imgSessionTriggerConfigure2 | Specifies each buffer is acquired based on a trigger. |
IMG_TRIG_ACTION_BUFLIST | imgSessionTriggerConfigure2 | Specifies acquisition of buffer list starts on a trigger. |
IMG_TRIG_ACTION_CAPTURE | imgSessionTriggerConfigure2 | Specifies trigger starts acquisition. |
IMG_TRIG_ACTION_NONE | imgSessionTriggerConfigure2 | Specifies triggering is disabled. |
IMG_TRIG_ACTION_STOP | imgSessionTriggerConfigure2 | Specifies trigger stops acquisition. |
IMG_TRIG_DRIVE_AQ_DONE | imgSessionTriggerDrive2 | Specifies that the trigger line is driven on AQ_DONE. |
IMG_TRIG_DRIVE_AQ_ IN_PROGRESS | imgSessionTriggerDrive2 | Specifies that the trigger line is driven on AQ_IN_PROGRESS. |
IMG_TRIG_DRIVE_ASSERTED | imgSessionTriggerDrive2 | Specifies to immediately drive the trigger line asserted. |
IMG_TRIG_DRIVE_DISABLED | imgSessionTriggerDrive2 | Specifies that the trigger line is not driven. |
IMG_TRIG_DRIVE_FRAME_DONE | imgSessionTriggerDrive2 | Specifies that the trigger line is driven with frame done. |
IMG_TRIG_DRIVE_FRAME_START | imgSessionTriggerDrive2 | Specifies that the trigger line is driven with frame start. |
IMG_TRIG_DRIVE_HSYNC | imgSessionTriggerDrive2 | Specifies that the trigger line is driven on HSYNC. |
IMG_TRIG_DRIVE_PIXEL_CLK | imgSessionTriggerDrive2 | Specifies that the trigger line is driven with pixel clock. |
IMG_TRIG_DRIVE_SCALED_ENCODER | imgSessionTriggerDrive2 | Specifies that the trigger line is driven with the scaled encoder signal. |
IMG_TRIG_DRIVE_UNASSERTED | imgSessionTriggerDrive2 | Specifies to immediately drive the trigger line unasserted. |
IMG_TRIG_DRIVE_VSYNC | imgSessionTriggerDrive2 | Specifies that the trigger line is driven on VSYNC. |
IMG_TRIG_POLAR_ACTIVEH | imgSessionTriggerConfigure2 imgSessionTriggerDrive2 imgSessionTriggerRead2 | Specifies the polarity of a trigger as active HIGH. |
IMG_TRIG_POLAR_ACTIVEL | imgSessionTriggerConfigure2 imgSessionTriggerDrive2 imgSessionTriggerRead2 | Specifies the polarity of a trigger as active LOW. |
imgPlot2_COLOR_RGB24 | imgPlot2 imgPlotDC2 | Specifies a 24-bit color RGB image. |
imgPlot2_COLOR_RGB32 | imgPlot2 imgPlotDC2 | Specifies a 32-bit color RGB image. |
imgPlot2_INVERT | imgPlot2 imgPlotDC2 | Specifies to invert the image when plotted. |
imgPlot2_MONO_10 | imgPlot2 imgPlotDC2 | Specifies a 10-bit monochrome image. |
imgPlot2_MONO_12 | imgPlot2 imgPlotDC2 | Specifies a 12-bit monochrome image. |
imgPlot2_MONO_14 | imgPlot2 imgPlotDC2 | Specifies a 14-bit monochrome image. |
imgPlot2_MONO_16 | imgPlot2 imgPlotDC2 | Specifies a 16-bit monochrome image. |
imgPlot2_MONO_32 | imgPlot2 imgPlotDC2 | Specifies a 32-bit monochrome image. |
imgPlot2_MONO_8 | imgPlot2 imgPlotDC2 | Specifies an 8-bit monochrome image. |
INTERFACE_NAME_SIZE | imgInterfaceQueryNames | Specifies the size of each array element in the interface names array. |
PULSE_MODE_SINGLE | imgPulseCreate2 | Specifies a single pulse that generates one pulse on the assertion edge of the specified signal. |
PULSE_MODE_SINGLE_REARM | imgPulseCreate2 | Specifies a pulse that generates a pulse on all assertion edges of the specified signal until imgPulseStop is called. |
PULSE_MODE_TRAIN | imgPulseCreate2 | Specifies a continuous pulse train that generates a pulse until imgPulseStop is called. |
PULSE_TIMEBASE_100KHZ | imgPulseCreate2 | Specifies a 100 kHz timebase to use for pulse generation. |
PULSE_TIMEBASE_50MHZ | imgPulseCreate2 | Specifies a 50 MHz timebase to use for pulse generation. |
PULSE_TIMEBASE_PIXELCLK | imgPulseCreate2 | Specifies the incoming pixel clock from the camera to use as a timebase for pulse generation. |
PULSE_TIMEBASE_SCALED_ENCODER | imgPulseCreate2 | Specifies scaled encoder counts as units for pulse generation. |