Dupline interface -
pacman
Posts: 327
Hi all.
I have an application where I would like to to interface to a dupline signal (http://www.dupline.com/scheletro.asp?Language=UK&page=1).
Dupline is (in essence) a 1kHz square wave signal (http://www.dupline.com/scheletro.asp?language=UK&Page=12).
Dupline uses a 2.2V level of off, anything higher is 'on'
I need to be 110% sure that my prop device does not influence the dupline - both under normal operating conditions AND should the prop device fail. So some form of opto isolation, zenners, resistor divider with really high impedance, magic capacitance isolator - circuit is required...
Has anyone (of us) done it before? Can you share your interface circuit?
Huge thanks in anticipation.
I have an application where I would like to to interface to a dupline signal (http://www.dupline.com/scheletro.asp?Language=UK&page=1).
Dupline is (in essence) a 1kHz square wave signal (http://www.dupline.com/scheletro.asp?language=UK&Page=12).
Dupline uses a 2.2V level of off, anything higher is 'on'
I need to be 110% sure that my prop device does not influence the dupline - both under normal operating conditions AND should the prop device fail. So some form of opto isolation, zenners, resistor divider with really high impedance, magic capacitance isolator - circuit is required...
Has anyone (of us) done it before? Can you share your interface circuit?
Huge thanks in anticipation.
Comments
I looked through the dupline website but within 5 minutes of searching I did'nt find any ELECTRICAL specifications.
But this is the key to it all.
From the fact that it uses a twisted pair-cable I assume it works with a current-driven interface as a current-driven interface in a twisted pair-cable is very robust against electrical noise.
What is against this is the comment of the developer that his ASIC-chip has a "low current consumption".
So if you already have a dupline-network
use an OpAmp as voltage-follower to connect to the dupline wire. To be 110% sure connect an Oscilloscope to the wires to see how the signal looks like.
Than connect it with the interface and see if the signal form changes.
To be 120% sure use an super-high-impedance oscilloscope with an input-impedance of 20 GigaOhm.
If you want to "listen" to an electric signal without influencing it you need a high input-impedance.
a first an easy attempt to this is a voltagefollower which provides high impedance which means minimal current and on the outputside
the same voltage as at the input.
If my explanation is still hard to understand for you I recommend to learn the basic of ANALOG elctronics like Ohms law etc.
before you start connecting your prop to the dupline-network.
best regards
Stefan