industrial rs485

[Mahyar-jafari]

hi guys
Im triynig to design industrial rs485 circuit ,I was asked to design Under the conditions below For safety and isolation:
 -Line voltage to RS485 and M-bus and Digital Input: 6 KV
 - RS485 and Digital Input to M-bus: 2 KV

What exactly does it mean?

What should I do to satisfy this requirement?

[jbb]

OK, this is about groups of signals and the strength of isolation between them.

I suggest you sketch out the different groups of signals and indicate the isolation required between them. That might clarity matters. Also, these look like surge levels, which have a big impact on clearances.  You should also determine the appropriate operating voltage levels, which have a big impact on creepage and materials selection.

I can say that 6kV isolation could be difficult. What’s happening with the power supply?

Once you know what isolation thingies (highly technical term), you can use the appropriate standard to turn the isolation levels into creepage and clearance rules for PCBs, enclosures etc.

[CM800]

I can suggest that In terms of RS485, the IC 'ADM2587EBRWZ' is a good place to start.
It's used in some of the products we sell, extremely reliable, isolated etc. Probibly one of the more robust chips on the market.

[Mahyar-jafari]

Can you explain more? What is the concept of isolation?

Where is it needed?

In addition to IC 'ADM2587EBRWZ', which circuits should I use for isolation?

[BNElecEng]

Hi Mahyar,

Take a look at this link: http://www.ti.com/lit/wp/slyy063/slyy063.pdf
It gives a good explanation about isolation, what it is and why it's needed.

Once you've read it, go back and read the data sheet of the ADM2587EBRWZ IC, it should hopefully make more sense. I can also recommend it for industrial RS485 applications. Page 18 of the datasheet gives you an idea of a typical application circuit.

Hope it helps