Real-Time System Components (RT Module)
A real-time system consists of software and hardware components. The software components include LabVIEW, the RT Engine, and the LabVIEW projects and VIs you create using LabVIEW. The hardware components of a real-time system include a host computer and an RT target. The following sections describe the different components of a real-time system.
Host Computer
The host computer is a computer with LabVIEW and the LabVIEW Real-Time Module installed on which you develop the VIs for the real-time system. After developing the real-time system VIs, you can download and run the VIs on RT targets. The host computer can run VIs that communicate with VIs running on RT targets to provide a user interface.
LabVIEW
You develop VIs with LabVIEW on the host computer. The Real-Time Module extends the capabilities of LabVIEW to allow you to select an RT target on which to run VIs.
LabVIEW Projects
Use LabVIEW projects to group LabVIEW files and non-LabVIEW files, create stand-alone real-time applications, and deploy or download VIs and other files to RT targets. When you save a project, LabVIEW creates a project file (.lvproj), which includes references to files in the project, configuration information, build information, and deployment information.
RT Engine
The RT Engine is a version of LabVIEW that runs on RT targets. The RT Engine runs the VIs you download to RT targets. The RT Engine provides deterministic real-time performance for the following reasons:
- The RT Engine runs on a real-time operating system (RTOS) or RTX subsystem, which ensures that the LabVIEW execution system and other services adhere to real-time operation.
- The RT Engine runs on RT Series hardware or the RT target on the RTX subsystem. Other applications or device drivers commonly found on the host computer do not run on RT targets. The absence of additional applications or devices means that a third-party application or driver does not impede the execution of VIs.
- RT targets on which the RT Engine runs do not use virtual memory, which eliminates a major source of unpredictability in deterministic systems.
RT Target
An RT target refers to RT Series hardware or the RTX subsytem that runs the RT Engine and VIs you create using LabVIEW. You can use two types of RT targets: networked RT Series devices and the RT target on an RTX subsytem.
Networked RT Series Devices (ETS)
A networked RT Series device is a networked hardware platform with an embedded processor and a real-time operating system that runs the RT Engine and LabVIEW VIs. You can use a separate host computer to communicate with and control VIs on a networked RT Series device through an Ethernet connection, but the device is an independent computer. Some examples of networked RT Series devices include the following:
- NI RT Series PXI Controller (ETS)—A networked device installed in an NI PXI chassis that communicates with NI PXI modules installed in the chassis. You can write VIs that use all the input/output (I/O) capabilities of the PXI modules, SCXI modules, and other signal conditioning devices installed in a PXI chassis. The RT Engine also supports features of the RT Series PXI controller. Refer to the National Instruments Web site at ni.com/info and enter the info code RT0001 for information about the features supported by the RT Engine on specific networked devices.
- NI RT Series [c]FP-2xxx (ETS)—A networked device thats runs the ETS RTOS.
- NI 1450 Series Compact Vision System (ETS)—An easy-to-use, distributed, real-time imaging system that acquires, processes, and displays images from IEEE 1394 cameras.
- Desktop PCs as RT Targets (ETS)—A desktop PC configured with RT Engine software. Refer to the Using Desktop PCs as RT Targets with the LabVIEW Real-Time Module document for information about desktop PC targets.
The LabVIEW Help does not contain hardware-related information about specific networked devices. Refer to the appropriate device documentation for information about the device.
RT Target on the RTX Subsystem (RTX)
When you use the LabVIEW Real-Time Module for RTX Targets, the RT Engine runs on the RTX subsytem of the host computer. The RTX subsytem creates the x:\RTXROOT directory, where x is the Windows root drive, to store all of the RT target files. Like RT Series hardware targets, the RTX subsytem provides a real-time platform under which you can execute LabVIEW VIs deterministically. You can communicate with and control VIs running on the RTX subsytem from LabVIEW in Windows.
VIs running on the RTX subsytem can use an NI PCI-7831 plug-in device for data acquisition.