I am new to USB communication. I am studying the USB communication and protocol. I have always wondered about how USB devices actually communicate. I have a microcontroller with USB peripheral. I am using this as device and PC as host for USB communication. Like, UART, the data(8 bits) are transmitted with start, stop and optional parity bit. But at they are excluded from the hardware of UART peripheral and we get ony 8 bit data. Similarly, how the data is transmitted or recieved in USB communication? Alo, if i want to implement MODBUS protocol with USB communication can it be possible? Or the USB protocol is mandatory to use with USB communication.

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    \$\begingroup\$ I think you need to read the USB documentation a bit more. The specifications will spell out both the physical layer (PHY) requirements and the encoding+protocol for the half-duplex USB 1/1.1/2.0 standards. \$\endgroup\$ – user2943160 Jul 15 '16 at 4:49
  • \$\begingroup\$ Thanks for response. Can u suggest any book or documentation for same? \$\endgroup\$ – Nama Jul 15 '16 at 4:54
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    \$\begingroup\$ Why not start with en.wikipedia.org/wiki/USB and usb.org ? They're the most immediate sources on the topic and can easily be found by doing some searching on the web. \$\endgroup\$ – user2943160 Jul 15 '16 at 5:04
  • \$\begingroup\$ This really is not a good type of question for this forum because there is no way to answer all your questions. You need to read up on USB. Start with these good web pages: beyondlogic.org/usbnutshell/usb1.shtml and janaxelson.com/usb.htm \$\endgroup\$ – Vince Patron Jul 15 '16 at 16:30
  • \$\begingroup\$ @Nama, please see electronics.stackexchange.com/help/how-to-ask Also see: electronics.stackexchange.com/help/on-topic The idea is that questions that can be learned by oneself are better learned by doing research (on the internet) There are plenty of resources available and us explaining them to you won't be useful. Plus answers can only be a few pages, explaining usb would be much more than a few pages. \$\endgroup\$ – Voltage Spike Jul 15 '16 at 18:11

"USB" actually defines SEVERAL of the lower levels of the "OSI 7 Layer Model". Physical, electrical, logical, etc.

if i want to implement MODBUS protocol with USB communication can it be possible?

Your question doesn't make sense as it stands. USB and Modbus each have their own DIFFERENT specs for physical, electrical, logical, etc. communication standards. Certainly, you could translate and make an adapter or interface between Modbus and USB. In fact there appear to be commercial products billed as Modbus to USB adapters.

Ref: https://en.wikipedia.org/wiki/OSI_model

Ref: https://en.wikipedia.org/wiki/USB

Ref: https://en.wikipedia.org/wiki/Modbus

Ref: http://www.schneider-electric.com/download/uk/en/details/643793054-TSXCUSBMBP-USB-Modbus-Plus-Communications-Adapter-Instruction-Sheet/


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