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6-1

6

Image Acquisition

This chapter contains information about acquiring images with the NI 17xx Smart Camera and 
explains the relationships between triggering, lighting, and exposure.

Exposure

The NI 17xx Smart Camera provides control of the image sensor exposure time through 
software. The exposure time is the amount of time that light is allowed to strike the sensor to 
produce an image. When light strikes the surface of the sensor, it dislodges electrons. As more 
light strikes the sensor, more electrons are freed, creating a charge on the sensor.

For a given amount of light, the sensor collects more charge during a longer exposure time than 
a shorter exposure time. Because the charge is what is read out to produce the image, it is 
important to have an optimal amount of light and exposure time for your application.

Exposing the image sensor for too short of a time relative to the amount of light in the 
environment results in a dark, low contrast image. Exposing the image sensor for too long of a 
time relative to the amount of light in the environment results in a bright, low contrast image. 
When the image sensor is exposed for an appropriate amount of time relative to the light in the 
environment, acquired images will exhibit appropriate contrast to easily distinguish both dark 
and light features. Contrast is a key factor in obtaining good results from image processing 
algorithms.

In applications where the object under inspection is moving, the exposure time must be carefully 
considered. If the object moves significantly during the exposure, the resulting image is blurry 
and unsuitable for processing.

The maximum exposure time for imaging a moving object without blurring depends on the per 
pixel spatial resolution and the rate of motion of the object. The per pixel spatial resolution is the 
field of view, calculated in the

Field of View

 section of Chapter 5, 

Image Sensor

, divided by the 

number of pixels in the sensor. Together, this information can be used to calculate the maximum 
exposure. Assuming the object is moving horizontally across the field of view, use Equation 6-1 
to calculate the maximum exposure time.

Содержание NI Vision 17 Series

Страница 1: ...ISC 1752...

Страница 2: ...NI Vision NI 17xx Smart Camera User Manual For NI 1712 1732 1752 1754 Smart Cameras NI 17xx User Manual February 2013 372429C 01...

Страница 3: ...and current events National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 683 0100 For further support information refer to the Technical Support...

Страница 4: ...nctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or...

Страница 5: ...HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE TO AVOID DAMAGE INJURY OR D...

Страница 6: ...e encouraged to try to correct the interference by one or more of the following measures Reorient the antenna of the receiver the device suffering interference Relocate the transmitter the device gene...

Страница 7: ...1 2 NI Desktop Power Supply 1 3 Third Party Power Supply 1 3 Power Requirements 1 5 Connect to the Development Computer 1 5 Direct Connection 1 5 Network Connection 1 6 Subnet Considerations 1 6 IP A...

Страница 8: ...iles 4 3 Selecting a Light 4 4 Connecting a Light to the Direct Drive Lighting Controller 4 5 External Lighting Controllers 4 5 Connecting an External Lighting Controller to the NI Smart Camera 4 7 Is...

Страница 9: ...LED Indicators and DIP Switches Understanding the LED Indicators 7 1 Device Initialization 7 2 POWER LED 7 2 STATUS LED 7 2 IMG ACQ LED 7 4 PASS LED 7 4 FAIL LED 7 4 Configuring DIP Switches 7 4 SAFE...

Страница 10: ...ilder AI B 1 The NI Smart Camera Restarts Unexpectedly B 2 Run Time Problems B 3 The NI Smart Camera is Unresponsive and Blinks the IMG ACQ and FAIL LEDsB 3 Lighting Problems B 3 The Light Does Not Il...

Страница 11: ...roduction to a key concept Italic text also denotes text that is a placeholder for a word or value that you must supply monospace Text in this font denotes text or characters that you should enter fro...

Страница 12: ...rmation about running applications created with Vision Builder for Automated Inspection in the Vision Builder Automated Inspection Interface LabVIEW and NI Vision Development Module Documents LabVIEW...

Страница 13: ...Reference Help Contains reference information about the LabVIEW VIs and properties for NI IMAQ driver software Measurement Automation Explorer Help for NI IMAQ Describes how to configure NI IMAQ drive...

Страница 14: ...ation Basic information about the NI 17xx Smart Camera hardware Instructions for configuring the NI 17xx Smart Camera hardware Basic information about software options for application development Inst...

Страница 15: ...eral different configurations When a feature pertains only to specific smart camera models a list at the beginning of the section shows which smart camera models support the feature All smart camera m...

Страница 16: ...ra also includes LEDs for communicating system status four DIP switches to specify startup options isolated inputs and isolated outputs for connecting to external devices Refer to Chapter 7 LED Indica...

Страница 17: ...1 2 NI 17xx Smart Camera 1 Connect and secure the 15 pin D SUB connector on the NI desktop power supply to the POWER I O connector on the smart camera 2 Plug the power supply power cord into the power...

Страница 18: ...ons for the POWER I O connector and lists the signal names and pin numbers used to supply power to the NI Smart Camera Refer to Chapter 3 Connectors for a complete description of pin functions for I O...

Страница 19: ...be output to the controller to prevent damage to the controller Use a power supply with tolerances that meet the requirements of the controller or use the 5 V external lighting strobe If you are using...

Страница 20: ...t If the NI 17xx Smart Camera is connected directly to the development computer the device will use a link local IP address If the NI 17xx Smart Camera is connected to a network that has a DHCP server...

Страница 21: ...pear in MAX or Vision Builder AI Note TA NI 17xx Smart Camera connected directly to the development computer or to the same subnet as the development computer is always configurable from MAX or Vision...

Страница 22: ...out using the NI 17xx Smart Camera with Vision Builder AI Refer to Configuring the NI Smart Camera with LabVIEW for information about using the NI 17xx Smart Camera with LabVIEW The installation and c...

Страница 23: ...ify that the device has power and is connected to an Ethernet port on the same subnet as the development computer then click Refresh Target List Refer to the section Understanding the LED Indicators i...

Страница 24: ...lete the following steps to acquire an image using Vision Builder AI 1 On the Vision Builder AI welcome screen select the NI 17xx Smart Camera in the list of targets 2 Click Acquire Image Smart Camera...

Страница 25: ...es for additional information about upgrading to the most recent version of LabVIEW Documentation for LabVIEW is available by selecting Start All Programs National Instruments LabVIEW LabVIEW Manuals...

Страница 26: ...ter a name for the device Use the Comments field to enter any additional information or a brief description of the device 4 Device names are limited to 31 characters with no spaces or special characte...

Страница 27: ...e click Finish Acquire an Image Complete the following steps to acquire an image using MAX 1 In the Remote Systems branch of the MAX configuration tree expand the folder for your device 2 Click cam0 N...

Страница 28: ...instructions for connecting the NI 17xx Smart Camera to external devices Information about acquiring an image with the NI 17xx Smart Camera Descriptions and blink code explanations for the LED indicat...

Страница 29: ...Camera Connector Overview Connector Name Connector Type Description POWER I O connector 15 pin D SUB Power and I O connection Lighting connector NI 780260 01 Lighting outputs from the NI Smart Camera...

Страница 30: ...uments Cables sold by other manufacturers could have different wire colors Table 3 2 POWER I O Connector Signal Descriptions Connector Diagram Signal Name Pin Number Wire Color 24 V 5 Red COM 15 Black...

Страница 31: ...g connector on the NI Smart Camera Caution All signals on the lighting connector are outputs from the smart camera Do not connect any external voltage or current source to any pin on the lighting conn...

Страница 32: ...ically detects the speed and duplex capabilities of its link partner and configures for the fastest common interface The smart camera can also perform auto crossover allowing the use of straight or cr...

Страница 33: ...etwork traffic that is not related to the smart camera traffic will often be present on the link In dedicated links between a computer and the smart camera typically the only traffic on the link will...

Страница 34: ...nd based on the average amount of power that can be safely dissipated by the light The Direct Drive controller can operate in continuous or strobed mode When operating in strobed mode the controller c...

Страница 35: ...e lighting controller in strobed mode care must be taken to ensure that the resulting strobe duty cycle and strobe duration do not violate the limits of the Direct Drive lighting controller or the lim...

Страница 36: ...n the lighting file is unusable because the data does not meet the requirements of Direct Drive lighting the data describing the light is not in the proper syntax or the digital signature has been alt...

Страница 37: ...certain lights with white and blue LEDs require a higher voltage drop than usual to turn on or reach full brightness Such lights may be incompatible with the smart camera These lights may need to be...

Страница 38: ...2 NI 1752 NI 1754 While the Direct Drive lighting controller is designed to handle common machine vision lighting requirements some applications require the use of a light with current or voltage requ...

Страница 39: ...the strobe timer in the controller Caution If you are using the 5 V strobe output or the 24 V strobe output the software does not impose any limits on the duration or the duty cycle of the strobe out...

Страница 40: ...NI Smart Camera Figure 4 3 Connecting an External Lighting Controller to the 24 V Strobe Output Isolated Inputs Caution Do not apply a voltage greater than 30 VDC to the isolated inputs Voltages grea...

Страница 41: ...sors to Isolated Inputs Isolated Outputs Caution The isolated inputs and outputs on the smart camera provide an easy means for preventing ground loops that could degrade signal integrity The isolation...

Страница 42: ...is connected to an output a large counter electomotive force may occur at switching time due to energy stored in the inductive load This flyback voltage can damage the outputs and the power supply To...

Страница 43: ...CONSOLE DIP switch is in the ON position you can read device information from the NI Smart Camera during startup such as the IP address and firmware version through a serial port terminal program Ens...

Страница 44: ...oise that would be eliminated by using a differential encoder Shielded encoder cables are recommended for all applications Unshielded cables are more susceptible to noise and can corrupt the encoder s...

Страница 45: ...and External Devices Figure 4 9 shows the internal quadrature encoder RS 422 input circuit Figure 4 9 NI Smart Camera Quadrature Encoder Input Circuit Phase A Phase A Phase B Phase B 3 3 V 10 k 10 k...

Страница 46: ...of view FOV of your imaging system use Equation 5 1 and the specifications for the image sensor of your device as listed in Appendix A Specifications 5 1 where FOV is the field of view in either the h...

Страница 47: ...ght combination of components that match your inspection needs This might include increasing your working distance choosing a lens with a shorter focal length or changing to a high resolution camera I...

Страница 48: ...igure 5 2b one half of the image is read out from the center of the sensor and the rest of the image is discarded to enable a faster start of the next frame In 1 4 scan only one quarter of the image i...

Страница 49: ...lipped to the maximum pixel value and you can no longer distinguish subtle shading in the brightest areas of the image Gain can be useful when there is not enough available light and you need to incre...

Страница 50: ...e smart camera configuration page to enable hardware binarization Refer to the Measurement Automation Explorer Help for NI IMAQ for more information Maintenance Do not touch the CCD sensor by hand or...

Страница 51: ...age Exposing the image sensor for too long of a time relative to the amount of light in the environment results in a bright low contrast image When the image sensor is exposed for an appropriate amoun...

Страница 52: ...to acquire images based on internal timing or an external trigger signal In both cases the NI 17xx Smart Camera can acquire images at the camera s maximum frame rate Refer to the Maximum Frame Rate se...

Страница 53: ...a configuration page Figure illustrates the relationship between an external trigger a lighting strobe and the exposure time Figure 6 1 Externally Triggered Mode The trigger shown in Figure represents...

Страница 54: ...re strobing a light there is a short delay while the lighting controller turns on the light This delay is represented by the lighting turn on time in Figure Table 6 2 lists the lighting turn on times...

Страница 55: ...rigger delay as described in the External Trigger section of this chapter Determining the Maximum Frame Rate You can determine the maximum frame rate for your configuration in software by reading the...

Страница 56: ...ger delay A longer exposure time results in a longer frame period and a slower maximum frame rate Determining the Trigger Delay If the trigger delay is set longer than the untriggered minimum frame pe...

Страница 57: ...the lighting turn on time respectively The image readout duration varies depending on the smart camera configuration as shown in Table 6 3 Table 6 3 Image Readout Duration Smart Camera Model Full Sca...

Страница 58: ...ides information about the location and functionality of the LED indicators and DIP switches on the NI Smart Camera Understanding the LED Indicators Figure 7 1 shows the location of the LEDs on the NI...

Страница 59: ...the smart camera waits up to 60 seconds to acquire an IP address If the smart camera does not receive an IP address within 60 seconds it connects to the network with a link local IP address with the...

Страница 60: ...apter 2 Software Overview for information about installing software on the smart camera 3 Flashes Green The smart camera is in safe mode because the SAFE MODE DIP switch is in the ON position Refer to...

Страница 61: ...temperature was exceeded Refer to the Thermal Considerations section of Chapter 8 Thermal Considerations and Mounting for information about measuring the temperature of the smart camera Refer to Appe...

Страница 62: ...4 x x Once you have reset the IP address you can set up a new network configuration for the smart camera from a development machine on the same subnet or you can use an Ethernet cable to connect the s...

Страница 63: ...hen powering up or restarting and will only display device information during startup When the CONSOLE switch is in the OFF position you can use the smart camera serial port and NI Serial driver softw...

Страница 64: ...specifications Figure 8 1 shows the location to take temperature measurements on the smart camera Figure 8 1 Measuring the NI Smart Camera Housing Temperature Operating the smart camera above the spe...

Страница 65: ...ting the NI Smart Camera Caution If you choose not to mount the NI Smart Camera to a thermally conductive structure do not position the smart camera with the heat sinks resting on any surface Doing so...

Страница 66: ...Smart Camera with Dimensions Figure 8 5 Bottom View of the NI Smart Camera with Dimensions 30 89 mm 1 216 in 32 80 mm 1 291 in 38 91 mm 1 532 in 50 62 mm 1 993 in 44 14 mm 1 738 in 117 66 mm 4 632 in...

Страница 67: ...verse polarity protection Yes Memory SDRAM 256 MB Nonvolatile program data memory 512 MB Image data storage Unlimited using FTP or an Ethernet hard drive Processor NI 1712 1732 Freescale PowerQUICC II...

Страница 68: ...Figure A 1 VGA Spectral Response Curve Gamma 1 0 fixed SXGA Sensor NI 1754 Only Sensor Sony CCD ICX205AL Active pixels SXGA Full scan 1 280 1 024 1 2 scan 1 280 512 1 4 scan 1 280 256 Binning 1 2 1 2...

Страница 69: ...68 s Exposure time increment 71 6 s Spectral characteristics Refer to Figure A 2 Figure A 2 SXGA Sensor Spectral Response Curve Gamma 1 0 fixed Lighting Direct Drive lighting controller NI 1752 1754...

Страница 70: ...VOL maximum 0 55 V IOH maximum 12 mA IOL maximum 12 mA 24 V external strobe NI 1732 1752 1754 Only Polarity Active high Strobe frequency Operating frame rate ON state Voltage Unregulated output drawn...

Страница 71: ...0 1 mA Input voltage 0 V to 1 V ON state Input current 3 mA to 5 4 mA Input voltage 20 V to 30 V Minimum pulse width 1 ms Isolated Outputs Channels NI 1712 1 NI 1732 1752 1754 2 Output type Sinking so...

Страница 72: ...10 Hz to 500 Hz 10 g Approved at altitudes up to 2 000 m Safety The NI Smart Camera meets the requirements of the following standards for safety and electrical equipment for measurement control and la...

Страница 73: ...minating certain hazardous substances from our products is beneficial to the environment and to NI customers For additional environmental information refer to the Minimize Our Environmental Impact web...

Страница 74: ...r DHCP use on your network or the DHCP server assigns the same IP address to another device Either remove or reconfigure the other device or reconfigure the smart camera to use a different IP address...

Страница 75: ...occurs when an attempt to upgrade the software is interrupted or if system files are deleted from the smart camera by the user Reinstall software on the smart camera Refer to Chapter 2 Software Overv...

Страница 76: ...he ambient temperature of the camera is the temperature inside the enclosure which can be notably warmer than the ambient temperature outside the enclosure 2 Measure the smart camera housing temperatu...

Страница 77: ...our lighting settings in MAX or Vision Builder AI You have requested an amount of current within the specified range of the smart camera and within the maximum lighting current settings you configured...

Страница 78: ...sion Builder AI Complete one of the following procedures to enable the correct lighting strobe MAX 1 Launch MAX 2 In the Configuration tree expand Devices and Interfaces 3 Expand NI IMAQ Devices 4 Exp...

Страница 79: ...ER LED is Not Lit When the NI Smart Camera is Powered On If the power supply is properly connected to the smart camera but the POWER LED does not light up check that the power supply is 24 V 20 15 and...

Страница 80: ...hase of most software products and bundles including NI Developer Suite NI also offers flexible extended contract options that guarantee your SSP benefits are available without interruption for as lon...

Страница 81: ...ght sensitive pixels on a CCD sensor B black level The value that corresponds to true black in the image C CCD Charge Coupled Device A chip that converts light into electronic signals E edge count A s...

Страница 82: ...mmission A standard setting body IEEE Institute of Electrical and Electronics Engineers A standard setting body I O Input output The transfer of data to from a computer system involving communications...

Страница 83: ...ght emitter to transmit signals to a light receiver which then enables a signal current P pixel pitch The distance between the centers of adjacent pixels in either the horizontal or vertical direction...

Страница 84: ...h an intermediate router SXGA sensor Super eXtended Graphics Array SXGA may refer to multiple resolutions SXGA sensors used with NI 17xx Smart Cameras feature a resolution of 1 280 960 pixels syntax S...

Страница 85: ...els VI Virtual Instrument A combination of hardware and or software elements typically used with a PC that has the functionality of a classic stand alone instrument W white level The point at which va...

Страница 86: ...devices 4 10 connecting lighting devices 4 1 connectors 3 1 I O 3 3 overview 3 1 power 3 3 CONSOLE DIP switch 7 6 conventions used in the manual xi D Declaration of Conformity NI resources C 1 device...

Страница 87: ...ional Instruments support and services C 1 network connection 1 5 NI 17xx binning 5 3 communicating with the console 4 10 connecting an external lighting controller 4 5 an isolated output to a sinking...

Страница 88: ...2 4 NI Vision Builder for Automated Inspection smart camera configuration 2 2 software NI resources C 1 SPEED LED 3 5 STATUS LED 7 2 indications 7 3 support technical C 1 SXGA sensor 5 1 T technical s...

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