Genicam gentl standard ver1.5 (1)

1. Introduce

GenICam GenTL The design goal of the standard is to provide a general method for enumerating devices connected to a known system , Communicate with one or more devices , If possible , From the device independent of the underlying transport technology to the host . This allows third-party software to , Use different technologies to control the camera and obtain data .

GenICam GenTL The core of the standard is to define a unified transport layer interface （TLI）. The software interface software between the transmission technology and the third party consists of a C Interface 、 A defined behavior and a set of standardized element names and their meanings . To access these features , Need to use GenICam GenApi modular

GenICam GenApi The module defines a XML Describe the file format , Used to describe how to access and control device functions . The standard feature naming convention defines the behavior of these functions .

GenTL The software interface does not include any remote device specific functions other than those used to establish communication .GenTL Provide a port that allows access through GenApi The module is connected to the remote device function . This makes GenTL Become connected to devices and stream data from them .GenApi and GenTL The combination of provides a complete software architecture to access devices （ For example, camera ）.

2. frame

This section provides a high-level perspective to help understand GenICam GenTL Different components of the standard .

2.1 overview

GenTL Our goal is to provide a transparent transport layer interface to obtain images or other data , And communicating with the device . Its purpose is not to configure the equipment except for transmission related functions , Even if it is necessary to use the configuration information to communicate with the device indirectly .

Producer consumer model diagram

When used alone ,GenTL It is often used to identify two different entities ：GenTL Producers and GenTL consumer .

One GenTL The producer is a software driver to implement GenTL Interfaces enable an application or software library to acquire or configure hardware , Or obtain the stream format image data of the device .

One GenTL Consumers are defined by GenTL Interfaces can use one or more GenTL Producer's software . For example, an application or a software library .

2.1.2GenICam GenApi

Emphasize that recommendations should not be made in GenTL Used in production realization GenApi modular

2.1.3 GenICam GenTL SFNC

In order to configure a GenTL producer , Each module implements virtual register mapping , And provides a GenApi Compatible XML file . In these XML In file , Only necessary （mandatory） Features will be described in this document . All features are described in GenTL SFNC In the document .

2.2 GenTL modular

GenTL The standard defines an implementation GenTL The hierarchical structure of the interface library . A module defines a layer . These modules show their hierarchical structure in a tree , Take the system module System Module As the root node of this tree .

 

2.2.1 System module System Module

For each GenTL consumer , The system modules that are the root of the hierarchy are to GenTL Producer Entry point for software drivers . It represents the whole system （ It's not the whole thing , Just from GenTL From the library's point of view , The entire host side GenTL View of the producer driver system .

The main task of the system module is to enumerate and instantiate the interfaces available in the implementation scope .

The system module also provides signal capability and module configuration GenTL The internal functions of consumers .

There can be one that contains multiple transport layers GenTL Manufacturers and represent them as different interface modules . In this case, the transport layer technology of the system module must “ blend ”（ See the first 6.6.1 Chapter ）, And the sub interface module discloses its actual transport layer technology . In this case, the first interface can be CamerLink Image acquisition board of , The second interface can be IIDC1394 controller .

2.2.2 Interface module Interface Module

The interface module represents a physical interface in the system . For Ethernet based transport layer technology, this will be a network interface card ; Based on CameraLink This will be an image data frame acquisition board . Enumerating and instantiating the available devices on this interface is the main role of this module . The interface module is also directed to GenTL The user provides signal and module configuration functions . One system may contain zero 、 One or more interfaces . An interface represents only one transport layer technology . It is not allowed to equip GigE Vision Camera and a CameraLink The camera is on the same interface . There is no logical limit to the number of interfaces addressed by the system . This is limited only by the hardware used .

2.2.3 Device modules Device Module

The device module represents a physical remote device GenTL Producer agent . The responsibility of the device module is to enable communication with remote devices for enumerating and instantiating data flow modules . The device module also provides the GenTL The user provides signal and module configuration functions . An interface module can contain zero 、 One or more device module instances . The device is always using a transport layer technology . For the number of devices connected to the interface , Logically unlimited , This is limited only by the hardware used .

2.2.4 Data flow module Data Stream Module

A single... From a remote device （ Images ） The data flow is represented by the data flow module . The purpose of this module is to provide the collection engine and maintain the internal buffer pool . besides , The data flow module also provides signals and modules GenTL Consumer configuration functions . A device can contain zero 、 One or more data streams . Logically, there is no limit to the number of streams a device can have , This is limited only by the hardware and implementation used .

2.2.5 Buffer module Buffer Module

The buffer module encapsulates a single memory buffer , As the storage destination of image acquisition data . Memory can be user allocated , It can also be GenTL Assigned by the producer . The latter can be pre allocated system memory .

The buffer module also provides signals and GenTL Consumer's module configuration function .

To enable data flow , At least one buffer must be advertised to the data flow module instance , And put it into the input buffer pool .

GenTL The producer can preprocess and format the image data of the changed image / Or buffer size . A detailed list of parameters , Please refer to the first 5.5 Chapter describes the buffer .

2.3 GenTL Module common part

The interaction and compatibility between producers and consumers are determined by C Interface 、 Description of module behavior 、 The signal 、 Configuration and collection engine guarantee .

 

2.3.1 C Interface

C Interface provide GenTL Producer's entry point . It enumerates and creates all module instances . It includes the acquisition processed by the data flow module . This GenTL The user can also access the signal and configuration interface of the module through C Interface . therefore , Use only C Interface can stream images , Independent of underlying technology .GenTL The default state of the producer should be to ensure that the device can be turned on and receive data from it . choice C The main reasons for interfaces are as follows ：

1. Support multiple client languages ：C Interface libraries can be composed of multiple programming languages . Basic types can be found in languages and modules （ Different heaps 、 Implementation details ）.
2. Dynamic loading of Libraries ： It's easy to dynamically load and invoke C Style function . This makes GenTL Users can dynamically load one or more of the runtime GenTL producer .
3. Scalability ：C Libraries can design early versions in a binary compatible manner . therefore , If the version changes , Consumers do not need to recompile .

Although for the above reasons C Interface , But actually GenTL Producer implementations can be done in object-oriented languages . Except for global functions , All interface functions work on handles that can be mapped to objects . Anything that can be used C The programming languages of the interface export library can be used to implement GenTL producer . To guarantee GenTL Producers and GenTL Consumer interchangeability , No language is needed to divide and ANSI C Compatible features , Specific functions can be used in the interface of GenTL producer .

2.3.2 To configure

Each module provides GenTL Port function , In order to GenICam GenApi（ Or any other similar non reference implementation ） Can be used to access the configuration of the module . This GenTL Producer The basic operations can be realized through C Interface completion does not require the use of specific module configurations . More complex or implementation specific can be used GenTL Ports through flexible GenApi Function interface to access functions and provide GenApi XML describe . Each module has this XML describe , The port of the module can be used to read and / Or modify the settings in the module . So , Each module has its own mapping that can be accessed by the virtual register port function . therefore , The configuration of accessing the remote device has been extended to the transport layer module itself .

2.3.3 The signal （ event ）

Each module can notify GenTL Consumer certain events . for instance , If new image data comes from a remote device , A new buffer event will be issued . The number of events supported by a particular module depends on the module and its implementation .C Interface makes GenTL Consumers can register events on the module . The event objects used depend on the platform and implementation , But encapsulated in C Interface .