- USB types vs. standards
- USB transmission standards
- Types of USB connectors
- Industrial applications of USB connectors
USB is a universal serial data transmission standard that we encounter every day. Currently, almost every device: computer, smartphone, printer, modem, TV set, external drive has one or more USB ports. The USB connector owes its popularity to its simplicity and versatility. At the turn of the 20th and 21st centuries, the rear panel of the computer was equipped with a variety of connectors – DIN plugs or parallel ports. The introduction of the USB standard allowed to replace all previously used ports with a single solution that is compatible with any connected device.
The USB standard is also very popular in industry. Here, as in the case of the consumer industry, simplicity and versatility prevailed. All transmission standards that have been used so far for communication between different machine components, controllers and sections of manufacturing lines can easily be replaced by one generally used standard. However, in order to properly connect different devices, it is worth knowing the basic types of USB connectors and transmission standards.
USB types vs. standards
When discussing the idea of connecting two devices with a USB cable, we must distinguish two concepts, namely the connector type and transmission standard. The type of the connector determines exactly the type of a USB socket and plug used. The transmission standard defines parameters such as bandwidth and maximum current. It is worth learning the difference between both terms in order to avoid unnecessary confusion and a common mistake of equating the USB 3.0 standard with the USB C-type connector, because these are not the same terms.
USB communication standards
The 1.0 standard launched in January 1996 was not available in many devices. The reason for this was the relatively low transmission speed and the lack of possibility to use any extensions and hubs. Only USB 1.1, which was released two years later, became a commonly used standard.
Although it has been in operation for almost 20 years, it is still widely applied in new devices. This standard provides a maximum bandwidth of 480 Mbit/s (High speed). USB 2.0 ports operate in a half-duplex mode, which means that at a given moment only one of the devices is allowed to send information. Only after the transmission is completed, the other device can start sending data. The maximum cable length in the 2.0 standard is 5m.
This standard appeared on the market as a successor to the 2.0 standard, offering a bandwidth of 5 Gbit/s (Super Speed). A new feature of this solution was the use of a full-duplex mode, in which both devices can simultaneously transmit and receive data. Additionally, the maximum current has been increased. The maximum cable length is 3m, which is a certain step back from the 2.0 standard. After the launch of USB 3.1, the 3.0 standard was renamed as USB 3.1 Gen 1.
It is an upgraded version of USB 3.0 and then 3.1. It offers a data transfer rate of 10 Gbit/s (Super Speed+) in the case of USB 3.1, and 20 Gbit/s (Super Speed+) in the case of USB 3.2. The 3.2 standard is basically identical to 3.1. The only difference is the implementation of multi-band transmission in the 3.2 standard, which allowed for a bandwidth increase. After the release of the 3.2 standard, USB 3.1 was renamed as USB 3.2 Gen 2, while USB 3.0 (USB 3.1 Gen 1) was renamed as USB 3.2 Gen 1. To make things more complicated, USB 3.2 is also called USB 3.2 Gen 2x2. The following table presents the naming methodology of USB standards.
|Current name||Previous name|
|USB 3.0||USB 3.2 Gen 1||USB 3.1 Gen 1|
|USB 3.1||USB 3.2 Gen 2||USB 3.1 Gen 2|
|USB 3.2||USB 3.2 Gen 2x2||-|
The USB4 standard specification was published on 29 August 2019. It is based on the Thunderbolt 3 transmission protocol and a data transfer rate of 40 Gbit/s. It is expected that the first devices equipped with USB4 connectors will be launched in 2021.
Types of USB connectors
Over the years, several types of USB connectors have been developed. Some of them were known for their application in specific devices, for example the Type-A connector can be found in computer mice, keyboards or flash drives, the Type-B USB connector was known for quite a long time mainly from printers, and the Micro-B USB connector was used in mobile phones. Currently, most types of USB connectors have already been officially withdrawn. Only USB C and USB A remain on the market, however, the latter will no longer be used in the USB4 standard.
USB Type-A connector
When you think about the USB interface, the first thing that comes to your mind is probably the standard, rectangular Type-A USB connector. It has been used since the creation of the standard. Most often we can find it in computers and mobile phone chargers. The blue colour of the plastic parts of the connector means that it supports the 3.0 to 3.2 standard.
USB Type-B connector
It is mainly known from printers and scanners. The connector that supports 3.0 and 3.1 standard also features blue plastic parts, the exception being the micro B plug. It does not have blue elements, but it is distinguished by its design, which somewhat resembles two micro B connectors combined together.
USB Type-AB connector
AB connector versions were only available as mini and micro subtypes and supported the 2.0 standard. Currently, they are very rarely used. Type-AB USB cable: CAB-USBAB0.5
USB Type-C connector
As the creators announced, Type-C is to replace all types of connectors that are currently used. This type of a connector has a symmetrical shape, thanks to which users will no longer need to be concerned with the plug orientation. Due to the fact that the Type-C connector is not backward compatible, the designers could implement several new interesting functions. One of them is USB Power Delivery, which allows charging any device with the current of up to 5A at 20V. Additionally, USB C is characterized by a twofold increase in data transfer speed. It is also worth mentioning that the C-type connector also supports the Thunderbolt 3 standard, whose bandwidth reaches 40 GB/s. Currently, Type-C-connectors are becoming more and more common. Initially, they were mainly applied in smartphones, but they already appear in laptops, desktops or external drives. If you want to install a USB port in your own device, it is worth considering Type-C connectors, because they will be the standard of the future.
Industrial applications of USB connectors
There are quite a few reasons why it is worth implementing solutions based on USB connectors in modern industry. One of them may be economic issues, as plugs and sockets of this type are currently not very expensive. Therefore, if there is such a possibility, it is worth using USB cables in all possible places, which will allow for the reduction of costs in the future.
Another important issue is the popularity of USB connectors among potential customers. If we manufacture a device equipped with a battery, which needs to be recharged from time to time, it is worth placing a dedicated USB port in the enclosure. Virtually everyone has a charger with a USB cable at home, thanks to which a potential customer won't have to buy a dedicated charger and will be able to use the one available at home.
In many companies, especially those originating from Japan, the 5S principle is applied. In general, the aim of 5S is to increase the safety and efficiency of workstations. One of the 5S elements is standardisation, which can also be the reason for using USB connectors. If your company operates a large number of devices that need to be interconnected, then according to the 5S philosophy you should use as few types of cables as possible. Most of the devices are currently equipped with USB ports, thanks to which the implementation of the standardization process can be significantly facilitated.
Apart from using USB cables, it is also worth paying attention to their optimal application. You have to consider carefully the distance over which data transmission will take place and the amount of information that will be transmitted. After collecting all the necessary information, it will be possible to choose the appropriate USB cables supporting the appropriate data transmission standard.