CVS - When an additional ISOLATED power supply is needed?

[Eblanco]

I need to make use of the digital I/O interface of my CVS. I´m planning to use relays/optocouplers instead of a direct wiring. So far I am considering a 24Vdc supply to power the CVS, and another one to power the coil side (in case of inputs) and contact side (in case of outputs) of the relays. My question is if by using a relay interface like this  i still need an isolated

power supply (a third one) or I can use the CVS supply (C,V) to wire the CISO and VISO terminals.

Any experienced opinion is wellcome. Thanks in advance for your replies.

[sankah2k]

Hi Eblanco,

It is always best to separate the power supplies to your CVS and the power to your digital outputs driving external I/Os (CISO and VISO). Apart from preventing any unnecessary damage to the CVS, it also makes sure that the power input to the CVS is uninterrupted in case of a failure/short and your inspection or other alarming steps could function despite the faulty circuit.

Hope this helps,

Cheers!

Sanka