Interfacing to a PCLD-785B ?

3 posts
by Mattylad » Tue Jun 26, 2012 8:51 pm
HI, while rooting through my junk I have found one of these:
Manual = ... D-785B.pdf

It is basically a 24 channel relay board that uses a 5V/TTL control logic.

How would I drive this using the Pi?
I.E. Is the Pi output 3v3 requiring a level shifter? If so what is the simplest way of achieving this?

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by TonyD » Wed Jun 27, 2012 11:55 am
The RPi only has 17 GPIO pins, so you'll only be able to control up to 17 relays from the 24 on the card. Unless you want to use a couple of I/O Port Expanders or a make a 24-ch serial-parallel I/F (using 3x 74HC595s).

Myself I would use 2x ULN2803 wired to 16 GPIO's of the RPi. Check out Grumpy_Mike Buffer Board or my MiniPiio_ULN2803.
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by Mattylad » Wed Jun 27, 2012 5:44 pm

It will likely go back down in the cellar for another 6 months before I can look at it again. :)
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