Wire transmission(15 mtrs) to send data & control signals for cascaded shift register

[Prakash12345]

Wire transmission(15 mtrs) to send data & control signals for cascaded shift register

I'm trying to send 4 kbps data from micro-controller(sender) to cascaded shift register IC(receiver).

In this scenario distance between micro-controller and shift register is 15 meters. On receiver side 512 shift register is arranged in cascading manner. I decided to use 15 meter wires with DB-15 connector with 15V and for data transmission MOSFET used on sender side. 15V is require to give power to other devices, other than data and control pins in DB-15 connector is used for other purposes. On receiver side 15V power source will be available and this 15V is powering the micro-controller.

My main doubt is, is there any data loss occur when we try to send data for 512 shift register arranged in cascade at 4 kbps over 15 meters of wire?
And which MOSFET is suitable for data transmission and idea for circuit designing in MOSFET side?

 

[barry]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

There are ICs specifically designed for transmitting and receiving data, e.g. RS422, why dont you use those? Why the mosfet?

 

[KlausST]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

Hi,

Show your circuit.

Klaus

 

[betwixt]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

I agree with Barry and Klaus. 15m isn't far and you might get away with normal cables at that distance but the risk is high, especially if there is interference nearby. A simple RS422 interface at each end will make it completely reliable, even over 10 times that distance for very little cost. Show us a simple schematic of the interface and power requirement so we can suggest suitable parts.

Brian.

 

[Prakash12345]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

I thought that sending data via MOSFET with little high voltage means there is no voltage lag or signal loss at sender & receiver side and also 3 phase- 5 HP motor will be placed in that room so only I decided to use MOSFET.
View attachment Schematic.BMP

 

[betwixt]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

MOSFETs come in many shapes and sizes but they are just transistors, they only work as part of a bigger circuit. You would have to show how you think one would work for us to advise you.

As long as you keep the wiring far enough away from a running 3-phase motor it will not cause any problems but if the motor is switched on or off you should expect spikes to corrupt the data. If you use RS422 as we suggested, it will not only make the link immune to interference, it will allow a small difference in ground voltages at each end. RS422 works on the relative voltages across two wires instead of the absolute voltage so it allows an overall shift in ground potentials between the two ends. You can use inexpensive CAT5 cable (network cable) for the link. Look at the data sheets for the ADM488/ADM489 for ideas, they are made by several companies.

Brian.

 

[Prakash12345]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

I'm in the stage of starting of my project so I didn't have circuit only prior idea.

You would have to show how you think one would work for us to advise you.

Thanks for understanding and I just want to make my project as simple.

On receiver side I using 15V so I went to CD4094 this would be capable of max 15V and most of the transceiver IC are not capable of operating Vcc at 15V so I choose MOSFET for data transmission in uni-direction.

I just confused that at 4 kbps speed, data would not correctly send to all 512 shift registers but I realized that there would not be data corrupt at this speed using RS422 standard. I learned new one ADM488/ADM489 differential line transceiver.

Last doubt and this may be silly question, can I change dedicated DB15 connector pins or CAT5 cable pins to my project. For ex. dedicated input pin may change to output pin and all may work as output at high data rate?

 

[KlausST]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

Hi,

On receiver side I using 15V so I went to CD4094 this would be capable of max 15V and most of the transceiver IC are not capable of operating Vcc at 15V so I choose MOSFET for data transmission in uni-direction.

Modern system tend to use lower voltages. Thus I ask myself why you go to that high voltage.

And this is exactly why we ask for more infirmations.
* it seems you have some existing circuit at the transmitter side
* it seems you have some existing circuit at the receiver side
Don't hide this information. If we know about this we can give better advice..

And you talk about MOSFET ... thus information is useless as long as we don't know how you connect it: N-Ch, P-Ch, high side, low side, push pull, open drain, open source....it could be anything.

So if you expect good advice you need to give good informations first.

Klaus

 

[Prakash12345]

Re: Wire transmission(15 mtrs) to send data & control signals for cascaded shift regi

Hi,

There is nothing to hide. My neighbor gave a project and the project was 'drip irrigation' that would give water for numerous plants separately according to time. Available control board was broken so I have to make that. For drip irrigation solenoid valve was controlling and control signal was given from the shift register(CD4094). So I was no rights to change the running system because it will make high investments and he won't allow me. Here the controller board is in plug and play, whenever he want to give water he has to plug in take it and this was in existing system. Then I asked the control board he said that he threw away because it was not working. His requirement is send signal within a second.

Coming to MOSFET, I thought it is better to use other than nothing.

So I too have no much information about this.