MGCsplit/MGCplus을 위한 ASAM-GDI 드라이버
자동차 산업 분야의 측정 환경은 측정 업무의 복잡성, 조합 된 제어 시스템과 데이터 관리의 일정한 증가에 의해 특징지어 집니다. 1998년, 이러한 상황은 잘 알려진 자동차 관련 제조사들에 의해 설립 된 ASAM(Association for Standardization of Automation and Measuring Systems)으로 이전 되었습니다.
The objective of this association is to create standards for data acquisition, automation and data management that enable measuring devices and software from different manufacturers to integrate more easily into complex measurement and control systems via standardized interfaces.
The application shown here presents the options available with ASAM-GDI (Generic Device Interface) for MGCsplit/MGCplus. The aim of the GDI is to allow standardized access to different devices when they are integrated into measuring and automation systems. Access is designed to be uniform and not specific to the computer platforms and operating systems being used. To achieve this, the communication functions (data transport) and the device functions (data to be exchanged) have been isolated from one another.
How does GDI work?
The application software no longer has to worry about the specific characteristics of the measuring devices. It parameterizes the measurements and reads the measurement data by executing functions provided by the GDI application program interface (GDI-API). It no longer needs to know which measuring device is sending the measured values. The measurement signals are merely addressed by names given to them by the user. GDI then translates all the application's queries into commands to the particular measuring system. The essential components of the GDI are the coordinator, the device drivers, the DCDs and the platform adapter.
The coordinator distributes the application's calls to the device drivers. A relevant driver must be integrated for each device type connected to the system. It translates the non device-specific coordinator calls to device-specific commands. The device commands are then converted by the platform adapter to operating system calls to operate the required interface (Ethernet, USB, ...).
So-called extensions can be integrated to allow functions to be implemented that are not defined in the GDI standard. Extensions typically come into play for network drivers, field buses, plug-in cards and software devices. Access to the extensions and to dynamic linking is standardized.To integrate a new measuring system into a GDI environment, you only need a device driver and a Device Capability Description (DCD) file, which are supplied by the equipment manufacturer. The device driver is also supplied as C/C++ source code, so that it can be used with different computer platforms and operating systems.
The essential advantages of GDI
- Only 1 more driver needs to be set up for each device
- Application design is not device-dependent.
This considerably reduces integration expenditure both for the user and for the device manufacturer!
Which device functions does the GDI driver for MGCplus support?
- With the aid of the GDI driver for MGCplus, all the measurement channels in the system can be uniquely identified by name. A measurement can then be compiled from the signals found in the device.
- The MGCplus option of measuring at up to three different sampling rates simultaneously is fully supported.
- Furthermore, detailed device error status information is made available to the application to enable the causes of any malfunction (parted cable, overload, etc.) to be quickly diagnosed.
- During measurement, important amplifier functions (e.g.: zeroing, taring, calibrating, etc.), can be initiated. T-ID™ functionality, as described on pages 7 and 24/25, is also supported.
GDI test bench at GM Powertrain, USA
Together with T-Systems, HBM concluded a project at General Motors, USA using the new GDI drivers for MGCplus. GM Powertrain develops automatic gearboxes and axle drives. To characterize these components in their dynamic behavior and with regard to their wear performance, GM Powertrain in Ypsilanti ran test cells that allow gearboxes to be tested under realistic dynamic load conditions - fully automatic, "24 hours a day".
MGCsplit with GDI for GM
The large majority of these test cells have since been equipped with MGCsplit systems and the test and automation system PTCU from T-Systems. As the data measured by MGCsplit is enlisted amongst other things for controlling the drive and braking loads, the real-time capability of the measurement and automation system was a central requirement.
The USB interface was therefore the one chosen for the transfer of measurement data. As one of the reasons why this was developed was the transfer of audio data, USB, unlike Ethernet, provides transfer mechanisms that have a guaranteed time response and are thus suitable for controller applications. Real-time data transfer has been implemented as a platform adapter extension for Linux and is used by the MGCplus GDI driver.
Data transfer in real time for more than 400 signals
To make test planning more flexible and to improve cell utilization, the test modules at GM, comprising the test piece, the requisite sensor technology and an MGCsplit, are delivered to the cells on a pallet with cabling pre-installed and calibrated. A further requirement therefore was an automation system that allows signal lists, test descriptions and monitoring functions to be reconfigured during routine operation.
In addition to this, it must be possible in test mode to transfer more than 400 signals at sampling rates of up to 19,200 Hz in real time from the MGCsplit systems to the automation system. The solution implemented by T-Systems and HBM meets these requirements for up to 4 MGCsplit data acquisition systems that can be connected to the automation system via a fiber-optic USB. The adopted USB solution allows not only synchronous data transfer of up to 750 kByte/s, but also allows MGCsplit devices to be plugged in and removed during routine operation.
The time delay between the sampling instant at the MGCsplit sensor input and the arrival of the measured values at the USB interface in the host system is max. 4 ms.
