Hi,

thank you for guides. I will try to use PC900 for isolating 1-wire communication. Do you have any schematics for doing this? Picture 14 from Dallas that Kai suggested is for com port - I need it for 8052 I/O port - shcematics with Tx and Rx on same I/O pin would be nice.

I'll use DS2450 with 4 single ended inputs and 4 op-amps (like OP90) to make diferential inputs. What is maximum voltage between channels? For example I want to measure 4-20mA thru 250 ohms. Each 250ohm resistor is connected to one diff. input. Let's say (worst case scenario) instrumentation loops 4-20mA are powered each from its power supply and not grounded, so voltage potencial between two loops can be high. Do I need to galvanic isolate channels or is using differential inputs and high input impedance op-amps enough?

Maybe I am complicating, but I really don't want to blow out the smoke from my IC's - or even worse from intrumentation loop IC's.

Thank you for sharing your experience.


regards, Damjan