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how to make serial cable <-> RJ45 cable

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pashok84

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Hi,

I want to connect my microcontroller board serial port with my laptop ethernet connector, as i don't have serial port in laptop.

How to connect serial port and ethernet cable.

In serial port i need only Tx, Rx and GND. i don't need RTS, CTS etc.

what is connection diagram?

How much RJ45 cable and jack will cost in india.

In laptop does it need any software / tweek to detect the ethernet cable as com port.

Thanks and Regards,
Ashok Kumar P
 

Hi,

How you are mingling serial communication with ethernet concept? Both are different standards. couldnt do this.
 

Ashok, these are COMPLETELY different communication systems, what you are asking for is impossibe,

At best, you might build an Ethernet interface using a microprocessor and provide it with a serial port so it can talk to your other board but you would also have to decide on IP addresses, protocols and so on. It would be as easy to add an Ethernet port directly to your existing board or to open up your laptop and wire a serial port into it.

I suggest you look at a different method, you can build or buy inexpensive USB to serial adapters. One of these will do what you want and will appear as a normal comms port on your laptop.

Brian.
 

Yes it does!

The YOST standard is for connecting one serial port to another using RJ45 connectors and CAT5 cable. It still needs a comms port at both end, it doesn't convert Ethernet to serial at all, it's just an alternative way of wiring what is normally done with 9 or 25-pin 'D' connectors.

Brian.
 

pashok84,

maybe is the best way for you to use USB converter to RS232 (serial port). I do not know where are you from, but that article is regular in computer shop, or some shop of electronics goods. You will get and CD (or DVD) with neccesary driver and I believe that will be a solution.

If you like electronics, you can build alone one USB converter to RS232. It is simple to find scheme of that on internet. There is one problem, you must use FTDI IC, and it is in SMD, but it is possible to solder on pcb, but you must be carefull. Driver for FTDI is available on the internet.
 

You can also get USB <--> Serial from PIC (They actually have a MCU with proper firmware loaded already, you just have to wire it up). Many companies have these kind of products, do some research. If you don't want to build your self, you can get ready made products (Local made in China, probably without any warranties) at nearly all computer markets. You can try your luck at Electronics superstore like Croma etc too. If you still are not able to get it, go to dealextream site, I am damn sure they'll have few cheap one (order 2-3, even if you'd need one).
Oh, almost forget to mention another beautiful DIY solution. Atmel AVR MCUs are easily available in many parts of India. Though they lack USB capablities, people have written SW USB stack for AVRs (search VUSB) which can add (LS) USB dev capabilities to AVRs.
 

I want to make onething clear is, i am not expecting ethernet data to be converted to serial data.

I want to DB9 in microcontroller side and RJ45 in PC side. opening hyperterminal i should see com port. com port is my communication.

The YOST standard is for connecting one serial port to another using RJ45 connectors and CAT5 cable. It still needs a comms port at both end, it doesn't convert Ethernet to serial at all, it's just an alternative way of wiring what is normally done with 9 or 25-pin 'D' connectors.
Brian.

Is it YOST communication is for?

is below configuration is possible?

PC < -- > DB9 < -- > RJ45 < -- > MAX232 < -- > mcu
 

Hi,

Yes. You can do this absolutely. There is readymade cable for DB9 to RJ-45 is available.
 

Hi Prakash,
Can you please provide link for those products and any circuit diagrams of it.

which side is DB9 comes on PC/mcu.
 

Hi,

I had get this from my touchscreen vendor, renuelectronics, pune. PC side, it is DB9 and on the MCU/Touchscreen side, it is RJ-45.
 

In this case, connection will be

DB9 RJ45
2(Rx) 3(Tx)
3(Tx) 6(Rx)
5(GND) 5(GND)

I can use the rest of the line in RJ45 for someother purpose (like connecting to LEDs, not to DB9 connector)
 

Hi,

Except the below pins, other pin you wont use. isnt it?.

DB9 RJ45
2(Rx) 3(Tx)
3(Tx) 6(Rx)
5(GND) 5(GND)


What you are asking? you can receive the data in rx and you can decode that data to drive LEDs.
 

The discussion seems reasonable if it refers to RJ45 as an alternative RS232 connector. Unfortunately the original posts asks for something different:
I want to connect my microcontroller board serial port with my laptop ethernet connector, as i don't have serial port in laptop.
Pashok84, have you changed your mind, or are you just confused about the capabilities of your notebook's RJ45 connector? It surely does not provide RS232 connectivity. Review the handbook in case of doubt, and please correct me if I'm wrong.
 

FvM, intially i was refering wrongly as RJ45 in laptop side, after this discussion, Now complete setup is

Laptop <--> USB to serial Converter < -- > RS232 DB9 connector < -- > circuit to connect RS232 to RJ45 lines < -- > RJ45 connector < -- > MCU

I am just wondering what will be the advantage of using RJ45 cable insteaded of RS232 cable.
small reduction in PCB size by using RJ45 connector insead of RS232 connector.
any other advantage????

is it adviseable to bring MAX232 IC to section "circuit to connect RS232 to RJ45 lines" in the above diagram and use serial line in TTL level in RJ45. this will help in removing the space required for MAX232 in my MCU PCB.

Please give ur comments.
 

Strictly spoken, RJ45 is a registered telephone jack standard and not the exact name for twisted pair Etherner connectors. Registered jack - Wikipedia, the free encyclopedia
use serial line in TTL level in RJ45
The popular RS232 over "RJ45" assignments are using RS232 level.
I am just wondering what will be the advantage of using RJ45 cable insteaded of RS232 cable.
Several interconnect standards are partly using P8C8 modular connectors and Ethernet cables, e.g. CAN Bus. Besides the ability of using standard connectors and cables, you can also share the infrastructure cabling in office buildings.
 

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