2nd opinion on Wiring diagram.. proximity - isolation - lpt.

[dazp1976]

Hello fellow members.
Just want to get a 2nd opinion on this wiring diagram below.
12 proximity sensors going into a 12 channel isolation board at 24v.
Then going out of the isolation board at 5v.
Then going from board directly into an input based LPT port of my cnc controller.


Sensors: NPN, NC, operating at 24v.
Isolator board designed for 24v/in & 5v/out.
LPT is port 5 of a UC300eth controller running at 5v.

Diagram:
30300






Yes it would be easier to get a bi-directional bob for it but we're talking about the u.k. here.
You can't get Jack.
(Anyway. The multi isolator boards look neater and are easier to get)

[m_c]

A quick scan looks OK.

However, what's with all the diodes?
On the input side, I could see sense in having LEDs for diagnostic purposes, but on the output/LPT side, they don't really serve much purpose.
Also, will the 5V on the LPT supply enough current for all the optos?

If you're worried about protecting the 5V, I'd think a 5.1V zener would provide more protection than a diode on every opto.

[dazp1976]

A quick scan looks OK.

However, what's with all the diodes?
On the input side, I could see sense in having LEDs for diagnostic purposes, but on the output/LPT side, they don't really serve much purpose.
Also, will the 5V on the LPT supply enough current for all the optos?

If you're worried about protecting the 5V, I'd think a 5.1V zener would provide more protection than a diode on every opto.
Hopefully this is relevent.

A quick read of 300eth manual again.
The 5v is a pass through from my seperate psu which is supplying it.

Into the controller from my psu (using a 5v 3A) to power it's logics and passing through to pin 26 for powering additional I/O.
States :Minimum for controller = 500ma. Higher needed for adding extra I/O.
Have a UCBB under power from Pin26 on port 1+2 already for axis controls (16 outputs - 18 inputs).
All output pins TTL max 20ma. Inputs TTL 0/5v levels.

Took the 5v in diagram from Pin 26 on port 5 for convenience due to it being right next to opto board in the box layout.
Psu itself is further away.