Communication with PLC using 4-5 digital inputs and some outputs??

[arunb]

Hi,

I would like to communicate with a PLC using parallel I/Os, I have 5 inputs and 1 output, Is there any standard method or protocol for doing this ???

I have thought of a scheme, for example when the PLC sends a numeric code (say 12), the 5 Input ports are set as 01100 (here 1- High, 0- Low), the 5 th input is pulsed from low to high (this is the strobe input), the inputs are captured after application of the strobe input.

The output is toggled low to high, indicating the input has been received.

I was wondering if there were any standard methods of communication that are used in PLCs.

thanks
aa

 

[JimB]

I would like to communicate with a PLC using parallel I/Os, I have 5 inputs and 1 output, Is there any standard method or protocol for doing this ???

I doubt it very much, seems a really crazy way to communicate.

I have thought of a scheme, for example when the PLC sends a numeric code (say 12), the 5 Input ports are set as 01100 (here 1- High, 0- Low), the 5 th input is pulsed from low to high (this is the strobe input), the inputs are captured after application of the strobe input.

The output is toggled low to high, indicating the input has been received.

At a quick guess, something like this could be made to work.

I was wondering if there were any standard methods of communication that are used in PLCs.

Yes there are, most PLCs have a serial communication port, often the same one used for the programming tool.
There are standard protocols, one commonly used protocol is MODBUS.

JimB