General FAQ
USB-inSync™ - What is USB-inSync™?
USB-inSync™ is a revolutionary technology which adds highly accurate timing and synchronization to the already powerful Universal Serial Bus (USB). While preserving all the features of USB, the enhanced capability of USB-inSync™ enables new applications and solutions never before possible.
ChronoLogic has developed the USB-inSync™ technology to transform the conventional asynchronous USB bus into a synchronous, deterministic and expandable control platform. Such capabilities were never envisaged by the inventors of USB. USB-inSync™ devices are fully compatible with USB and possess all the standard connectivity characteristics of USB. In addition to this, USB-inSync™ devices feature highly accurate synchronization and deterministic timing capabilities.
Each USB-inSync™ device is equipped with a local clock that is accurately phase locked to that of every other USB-inSync™ device attached to a given Host PC. A deterministic triggering system is also provided such that processes can be started and stopped in a precisely controlled manner. These two features extend USB beyond the realms of its original concept and allow new synchronization, control and monitoring possibilities within a distributed PC-based environment.
ChronoLogic has therefore created a powerful extension to USB enabling a range of test & measurement applications which require coordinated multi-device control and data acquisition.
For more detail on the features and benefits of USB-inSync™ see the “Synchronization/Precision Timing” page and the “What is USB-inSync™” white paper.
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Why do we need USB-inSync™?
USB-inSync™ is a powerful and revolutionary new technology that transforms the standard USB port into a synchronous, deterministic and expandable control platform. While the conventional USB port is a consumer friendly, hot-swappable platform that offers users an easy to use, plug-and-play external connection to the computer, it has limited ability to synchronize multiple devices.
In order to perform high precision control, data acquisition or test & measurement applications using multiple devices and the USB port, USB-inSync™ technology is essential. USB-inSync™ maintains all of the consumer friendly benefits of the USB port, and enables it as a highly accurate instrumentation and timing bus.
As USB instrumentation devices increase in popularity, USB-inSync™ will become essential to provide users with the precision and control capability they require for control, data acquisition, and test & measurement applications.
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Can I connect a ChronoLogic USB-inSync™ device to a standard USB port?
Yes. ChronoLogic USB-inSync™ devices connect via standard USB ports and standard USB cables. ChronoLogic is currently in development of a new, 24 bit data acquisition module, which will also offer a rugged USB connector and USB cable to enable its use in rack based, industrial applications.
Is USB-inSync™ compatible with my existing test & measurement setup?
Yes. ChronoLogic’s USB-inSync™ products utilise the standard USB port, therefore all of ChronoLogic’s modules are compatible with an existing PC-based test & measurement setup.
Is any device / instrument with a USB port a USB-inSync™ instrument?
No. Due to the useability and plug-and-play capability of USB, there are an increasing number of USB devices / instruments on the market. None of these devices offer users the distributed synchronization, timing or accuracy benefits offered by ChronoLogic’s USB-inSync™ instruments.
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What benefits does USB-inSync™ provide to test developers?
ChronoLogic’s USB-inSync™ devices offer test developers all of the plug-and-play benefits of USB with the added benefit of distributed, synchronized, precision timing accurate to nanosecond levels across their entire USB test setup.
The proven benefits of using traditional USB instruments include:
• External serial bus which frees IRQ resources for other devices
• Hi-Speed 480Mbps bandwidth - USB 2.0 (proposed 4.8Gbps - USB 3.0)
• Hot-swappable, plug-n-play operation
• Reliability is assured through automatic error correction protocols
• Expansion via inexpensive random star topology
• Global PC compatibility & low Cost
• USB-inSync™ devices provide developers with a broad range of specific benefits over traditional USB instruments:
• Nanosecond phase-locking between USB-inSync™ devices on the same USB hub
• Nanosecond phase-compensation between expansion hubs (using ChronoLogic Master Hub)
• Real-time sampling capabilities
• COM API interfaces with most modern software application
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Why do we need precision timing and synchronization in test & measurement applications?
Precision timing is very important in test and measurement applications because errors in timing translate directly into measurement error. The example below shows how timing errors transform directly into measurement errors. If the clock circuitry of a measurement device has jitter T, then the measurement can be either before or after the ideal time by ½ T, which results in a measurement error.
In the case of Data Acquisition instruments, such timing errors can result in a significant loss of accuracy and increase in signal distortion. For example a 16-bit data acquisition device with a poorly controlled sample clock may not be as accurate as a 10- or 12-bit device with a well controlled clock. As such, a device’s clock performance (jitter) is one of the most important specifications to consider when selecting equipment.
Synchronization of multiple instruments is essential when multiple devices are required to measure a given installation. It is very difficult to correlate measurements from multiple devices if they all operate on a different time-base and the start time of the acquisition is not synchronized. Furthermore, synchronizing even a single instrument with an experiment is often important to guarantee that data is appropriately recorded.
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How does USB-inSync™ trigger its modules?
USB-inSync™ is a time-based platform in much the same way as LXI. Each ChronoLogic USB-inSync™ device in a given network contains a synchronized clock and real-time register. All attached devices share a common notion of time, which may additionally be synchronized to any external reference time such as the global GPS time.
Devices are programmed to respond to time triggers. At the appointed ‘time’ each device executes its pre-programmed instructions. Time-based controls offer increased flexibility and new opportunities for test engineers.
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USB
Can I run multiple USB devices on my computer concurrently?
Yes. One of the significant advantages of the Universal Serial Bus (USB) is that it is an expandable interface. USB is a serial bus designed to operate in a point-to-point, PC-centric, host-slave configuration (see diagram below). One USB port is capable of controlling up to 127 devices (including expansion hubs) from a single USB Host Controller on a PC. Each hub may have up to 7 expansion ports and can be connected to other hubs in any random topology the user desires.
By using ChronoLogic’s USB-inSync™ devices, including the Maestro Master Hub, the USB port is capable of controlling up to 127 devices in a synchronous and deterministic manner with very high levels of accuracy.
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Are the ChronoLogic USB-inSync™ modules compatible with USB 1.1 or 2.0?
ChronoLogic devices are fully compatible with USB 2.0 which offers high speed data transfer up to 480Mbps. The ChronoLogic products are not compatible with USB 1.0 or 1.1 hosts as they require the USB 2.0 protocol to enable their synchronization capability.
Despite this we can meet the requirements of USB full speed (often referred to as USB 1.1) if required for a specific custom application.
Will ChronoLogic offer devices that will be compatible with the USB 3.0 standard when it becomes available?
The USB 3.0 Specification is still in its draft stage, but ChronoLogic will be developing products that feature the USB 3.0 interface.
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What advantages will USB 3.0 offer for instrumentation applications when it is available?
The release of USB 3.0 will be the catalyst for massive growth in USB instrumentation. There is strong demand already for USB instrumentation and the new standard offers many advantages.
Bandwidth increased to 4.8 Gb/s
• 10x increase in data throughput
• Capacity for more data intensive test applications
Lower bus latency
Optical cables
• Offers extended range without repeaters
• Noise immunity (for application in harsh environments)
• Isolation between device and PC (for self powered devices)
Better Synchronization for USB-inSync™ Generation III
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Why is USB a good choice for Data Acquisition?
The Universal Serial Bus (USB) interface is ideal for data acquisition (DAQ) applications because USB offers plug-and-play capabilities that allow easy setup and high portability. USB DAQ devices can also be “hot-swapped” without the need to re-boot your computer, and do not need to be rack-mounted, allowing for easier customisation and flexibility in the users test setup. In addition to that, the USB port is a global standard for PC with every PC currently sold offering USB ports.
The USB 2.0 standard has also significantly increased the data transfer rate of USB devices to 480Mbps, greatly improving the functionality and range of applications of USB data acquisition devices. This will be further improved with the implementation of USB 3.0 in the future.
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What is the distance limit between my host computer and the ChronoLogic devices?
The USB specification states that a USB cable length cannot be greater than 5m. It also specifies that there can be up to a maximum of 5 hubs on any 1 USB port. This means that the maximum allowable radius around the PC is 30m.
While this will be sufficient for the majority of applications, ChronoLogic has developed a new product called the ‘Sonda’ which allows users to provide synchronous clock and timing signals across distances of up to 100m.
For more information on the ‘Sonda’ and its application in widely distributed environments, please visit the “Application Centre”.
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What is DVI?
DVI is an acronym for Distributed Virtual Instruments, and is ChronoLogic’s latest USB-inSync enabled product range. The DVI range provides users the ultimate in test & measurement flexibility, by enabling synchronized, multi-device, distributed applications in a virtual instrumentation (or PC-based) environment.
Each DVI is a stand alone unit that provides a specific functionality in a small, rugged & stackable form factor with all of the plug-and-play benefits of USB. In addition, DVI’s may be combined with ChronoLogic’s Maestro – Master Timing Hub and used as building blocks to create large, synchronous test setups consisting over more than 100 devices with multiple functionalities.
By combining DVI hardware with ChronoLogic’s free software programs or LabVIEW drivers (provided), multiple modules can be controlled as one synchronous, multi-function device. This is possible due to the fact that each DVI is enabled with USB-inSync™ technology, which allows multiple USB modules to be synchronized to within ±1ns. Such precision timing capability has traditionally been limited to expensive, fixed rack-based instrumentation platforms.
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Applications
What are some typical applications in which the ChronoLogic USB devices can be used?
ChronoLogic’s USB-inSync™ devices can be used in a large and diverse range of test, measurement, control & automation applications. This is due to their ability to generate a synchronous sequence of events, and synchronously measure distributed inputs and outputs using a modular, PC-based instrument solution.
Because ChronoLogic devices allow users to develop and customise a distributed instrumentation solution, they provide the ability to create new applications in a flexible, distributed and synchronous way, whilst enjoying all of the capabilities of the user-friendly USB port.
For a range of detailed application examples, including diagrams, please visit the “Application Centre”.
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ChronoLogic Hardware & Software
Are the ChronoLogic USB devices certified to regulatory standards?
ChronoLogic devices comply with all required regulatory standards. ChronoLogic is certified to ISO 9001:2000 and maintains commitment to design and manufacture to the highest quality standards. ChronoLogic also provides voluntary compliance with RoHS.
For further detail on individual standards and compliance for specific ChronoLogic products, please refer to the “ChronoLogic User Manual”.
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Do ChronoLogic USB devices come with their own software?
Yes. All ChronoLogic devices come with the ChronoLogic software platform. The ChronoLogic software platform is based on our multiple device threaded digital I/O command infrastructure. A simple to use Graphical User Interface (GUI) called Control Center is included. Control Center empowers the user to start acquiring data from ChronoLogic USB-inSync™ enabled devices within minutes of opening the box.
Advanced users are provided with access to extended low-level device functionality through our COM Server. This enables interfacing through Windows based software application including MS Office, Visual Studio and National Instruments LabVIEW™.
Additional LabVIEW™ device drivers are available so that USB-inSync™ devices can be quickly implemented within an existing test environment. OEM users benefit from the flexibility of multiple software interfaces to create application specific solutions.
The software platform features are summarised as follows:
• Fully compatible with USB2.0 driver specification
• COM Server interface for end user customisation
• Drivers for industry standard interfaces such as LabVIEW™
• Links multiple USB-inSync™ modules with multiple concurrent software applications.
• Enables complete USB-inSync™ functionality
• Includes Registration manager, Message processor, Event handler
• Threaded I/O processing for synchronous sampling or deterministic control applications
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Can I use the ChronoLogic software platform to develop my own custom software for specific applications like I can with LabVIEW?
Yes. ChronoLogic supply a COM interface to their software, as well as example code and documentation for C#, C++, VisualBasic.Net and LabVIEW™. For further information about developing custom software using ChronoLogic’s software platform, please refer to the “Chronologic User Manual”.
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Which operating systems are supported by the ChronoLogic USB devices and associated software?
Currently all ChronoLogic devices require Windows operating systems. They require Windows XP or higher.
ChronoLogic is currently working on a version of our software that will be compatible with the Linux operating system.
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Do any ChronoLogic USB devices offer isolation?
Yes. All ChronoLogic USB Instruments offer isolation between the PC and devices under test. This is extremely important for instrumentation but only a few vendors offer this as standard.
Isolation is critical for prevention of ground loops that can occur when distributed devices are grounded at multiple points. Ground loops result in slight voltage offsets and can inject noise into the measurement equipment or the device under test.
Furthermore isolation protects both the PC and attached devices. A significant voltage can exist across the ground potential in a distributed measurement environment. Inadvertent connection of these differing potentials can cause damage not only to the PC and USB device, but also any equipment connected to the network.
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What drivers are used by the ChronoLogic Software?
ChronoLogic develops and supplies its own kernel mode drivers for its devices. These drivers are installed when the ChronoLogic software is installed on your computer.
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Trouble Shooting
My Control Center software can’t find my ChronoLogic device. How can I fix the problem?
Steps to try:
• Unplug and re-plug in the device.
• Un-power and re-power the Master Hub, if there is one.
• Re-start Control Center
• Reboot the computer
• Uninstall the device using Windows device manager
• Uninstall Control Center and re-install
If you are still encountering problems, please contact “Technical Support”
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I have installed a software upgrade but there has been no change in functionality. How can I ‘activate’ the upgrade?
In order to activate all software upgrades, the ChronoLogic USB modules must be unplugged, and re-plugged in. This allows the drivers to be updated.
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