PiFaceRelayPlus addressing

Pat,

as far as what I know and have tested with several PiFace boards, every board has onboard a couple of jumpers to setup the addressing so you can stack more than one but there is a limit of 8 boards max.

The following image shows how the address bits can be set on the PiFace relay board:

while this is the link where you can download the complete manual of the board: http://www.piface.org.uk/assets/docs/PiFace-Relay-Plus_getting-started.pdf

Always on the same mentioned manual, there is a paragraph reporting the following:

your Relay+.

pfr = pifacerelayplus.PiFaceRelayPlus(pifacerelayplus.RELAY)

In this line the pifacerelayplus.RELAY refers to any PiFace EXTRA board you have

attached. Refer to that EXTRA board’s documentation for what you should put here.

Then toggle (switches between off and on) the first relay, pause to see the result and then toggle

it again with the following code:

pfr.relays[0].toggle()

time.sleep(2)

pfr.relays[0].toggle()

Save your program by pressing CtrlX

then Y. Now run your program in the Terminal window to

see LED0 flash and hear Relay0 click by typing the following:

python3 relayonoff.py

This means that if you have more than one stacked board, you simply should see more than the single board relays that - depending on the different sequential stacked boards addressing - are numbered in sequence. This is valid as general case but you should make a test in your specific case because I have not many relay boards here to test.

These are links that I hope maybe useful:

http://www.raspberryconnect.com/hardware-add-ons/item/156-piface-digital

This is instead a link to the PiFace forum where it is explained how to address different boards: https://pifacedigital.wordpress.com/about/

If this method does not works in Python it is possible that you should make a small change in the corresponding C++ library but probably it works.

Enrico

Thanks Peter and Enrico. I was looking at it as though you select the address and then access one of the relays relating to that addressed board. By what Enrico has posted it looks like the relays are just added to the original relay count. It will be interesting to see what happens when for example if I have the PiFaceRelayExtra board added (relays 0-7) and add another PiFaceRelayPlus board so that gives me relays 0 - 11 vs just two PiFaceRelayPlus boards (without the PiFaceRelayExtra board). Does the count go 0-7 again or does it go 0-3 and 8-11.

It's would be a much easier and neater solution to have the boards individual address called and then select which relay you want on that board.

Also when stacking the boards, do the GPIO pins get addressed the same way? There doesnt seem to be a lot of in depth info on these boards. Its a shame there isnt a schematic available too

Thanks Peter and Enrico. I was looking at it as though you select the address and then access one of the relays relating to that addressed board. By what Enrico has posted it looks like the relays are just added to the original relay count. It will be interesting to see what happens when for example if I have the PiFaceRelayExtra board added (relays 0-7) and add another PiFaceRelayPlus board so that gives me relays 0 - 11 vs just two PiFaceRelayPlus boards (without the PiFaceRelayExtra board). Does the count go 0-7 again or does it go 0-3 and 8-11.

It's would be a much easier and neater solution to have the boards individual address called and then select which relay you want on that board.

Also when stacking the boards, do the GPIO pins get addressed the same way? There doesnt seem to be a lot of in depth info on these boards. Its a shame there isnt a schematic available too

using your own program you could do that, but the library provided treats them as a contigious set of relays, the trick is to know the address of each board in the stack