Bill Greer, senior product specialist, Contemporary Controls
Various networking technologies specify that stations must be separated by some minimum distance. Occasionally a customer is surprised about the lack of a minimum length requirement for their Cat 5 cable that connects one Industrial Ethernet device to another.
Network cable minimum length specifications arise because of an impedance mismatch between elements in the signal path. When electrical energy is transmitted through a cable, some of it is not absorbed by the receiving station and is instead 'reflected' back to the source. This reflected energy disturbs the purity of the signal - and if the effect is of sufficient magnitude, the signal can be degraded to the extent that its information is corrupted or even useless. If source and destination transceiver impedances match the impedance of the cable itself, there is no reflected energy and signal energy is delivered completely.
Reflected signal is always an issue in a bus topology because only the end devices have transceiver impedance values that match the impedance of the cable. Mid-bus device transceivers must have higher impedance values to avoid 'loading' the cable (preventing proper signal delivery to devices further along the bus). Thus, a mid-bus device transceiver presents an impedance mismatch to the cable and inevitably creates some degree of reflected energy. To keep the reflected energy to acceptable levels, a bus protocol will specify a minimum length of cable that separates two bus devices.
Industrial Ethernet uses a star topology in which devices exist only at each end of a cable. With this topology, both transceiver impedances match the cable impedance and no appreciable signal reflection occurs. This lack of signal reflection is true whether the devices are separated by 100 m or 100 mm. Therefore, there is no need to specify a minimum cable length.
Next-gen modules for rugged edge AI systems Altron Arrow
Computer/Embedded Technology
Designed for real-world edge deployments where systems do not sit still, SolidRun’s P100 COMx6 series targets mobile platforms as well as harsh, mission-critical environments.
Read more...Fanless multimedia edge PC Vepac Electronics
Computer/Embedded Technology
Dual 4K display capabilities, ultra-efficient processing, and versatile mounting options make the Intelli TWL01 Edge the ultimate embedded platform for multimedia solution building.
Read more...Fanless multimedia edge PC Future Electronics
Computer/Embedded Technology
Dual 4K display capabilities, ultra-efficient processing, and versatile mounting options make the Intelli TWL01 Edge the ultimate embedded platform for multimedia solution building.
Read more...A software-based controller for the industrial future Phoenix Contact
Computer/Embedded Technology
With Virtual PLCnext Control, Phoenix Contact is launching a software-based controller solution that enables flexible automation functions in virtualised IT environments.
Read more...5G mobile hotspot with integrated multimodal AI capabilities CST Electronics
Computer/Embedded Technology
MeiG Smart has launched its first 5G Mobile HotSpot solution, the SRT8710, a breakthrough in mobile connectivity that combines ultra-fast 5G communications with integrated multimodal artificial intelligence functions.
Read more...Panasonic TOUGHBOOK 33 2-in-1 detachable Vepac Electronics
Computer/Embedded Technology
The Panasonic TOUGHBOOK 33 is a fully rugged 12-inch 2-in-1 detachable notebook designed to deliver unmatched flexibility, durability, and performance for mobile professionals working in demanding environments.
Read more...SBC with 12 TOPS computing power iCorp Technologies
Computer/Embedded Technology
The QSM560DR series is Quectel’s multi-mode 5G smart control panel with built-in Ubuntu/Android/Windows operating system based on the Quectel SG560D series smart module.
Read more...High-performance µC series NuVision Electronics
Computer/Embedded Technology
GigaDevice has announced the official launch of the GD32F503/505 high-performance series of 32-bit general-purpose microcontrollers based on the Arm Cortex-M33 core.
Read more...Octa-core smart development board iCorp Technologies
Computer/Embedded Technology
The QuecPi Alpha smart MOB development board is Quectel’s smart development board based on Qualcomm’s QCS6490 high-performance 64-bit octa-core processor.
Read more...Vertiv expands rack PDU portfolio
Computer/Embedded Technology
Vertiv has announced its new Vertiv PowerIT rack power distribution units designed to address the rising power needs of data-intensive workloads, including AI and high-performance computing.
While every effort has been made to ensure the accuracy of the information contained herein, the publisher and its agents cannot be held responsible for any errors contained, or any loss incurred as a result. Articles published do not necessarily reflect the views of the publishers. The editor reserves the right to alter or cut copy. Articles submitted are deemed to have been cleared for publication. Advertisements and company contact details are published as provided by the advertiser. Technews Publishing (Pty) Ltd cannot be held responsible for the accuracy or veracity of supplied material.
printer friendly version