Seeking an I2C 8-16 channel relay board

We have need for relay boards driven by I2C; that being a task for the Meg2560 box.

I've turned over rocks hither and yon, and spotted many "close" but few successes. There are lots of non-I2C relay boards which seach engines insist on showing me. Then there are I2C decoders with no relays. I've found one in the Pacific rim but they want more to ship than the board costs.

Basic needs:

  • I2C in
  • In/out I2C connections (daisy chain)
  • programmable address (we'll have 4-8 boards on a system.)
  • Compact.
  • SPDT relays, 1A+
  • rational shipping costs.
  • DIN rail mounting*
  • 24V relay supply*

Starred items might be sacrificed; i.e. I can find a generic DIN foot, use an external 24->12V regulator, etc.

Any suggestions for someone manufacturing boards meeting these demands?
Thanks

Does it have to be I2C.

CrossRoads (moderator here) sells 8-relay boards with shift registers.

http://www.crossroadsfencing.com/BobuinoRev17/

Leo..

Yes, I2C. Our choices were I2C or SPI; I2C looks better to us.
We'll be driving 4-8 of the boards (32-64 relays) with the system.
We may actually end up with >8 boards eventually.

There's nice ones at https://www.ereshop.com/shop/free/I2C-RL8xxM_SHEET.pdf but the shipping is a killer.

Our supply is 2 x 13.8vdc AGM batteries.

CRC_failure:
I2C looks better to us.

In what way?

Shift registers can be controlled with (8Mhz) SPI.

Design your own relay board with e.g. a TPIC6C596.
Leo..

The Mega system we are using has I2C available to us.
We are already using its digital outputs for other functions.

We do not want to design & manufacture our own boards; we want to buy them as needed.

I don't know, I'd go with SPI, fast, easy to control.

digitalWrite (ssPin, LOW);
SPI.transfer(on_off_state0); // repeat for each board
digitalWrite (ssPin, HIGH);


Here are 3 daisychained, got lazy with the code example and didn't them unique

Can use shiftOut() also if the D50-53 pins are not available for SPI on the Mega.

CrossRoads:
Can use shiftOut() also if the D50-53 pins are not available for SPI on the Mega.

Not familiar with the board shown. Is it SPDT? Contact rating? We'll have up to 64 channels we're switching. We debated which output to use but at the time we didn't find any more SPI boards than I2C.

Is it SPDT? Contact rating?

Your basic observational powers are severely lacking... it's a custom board with a very nice photo that had you spent 5 seconds observing said photo you could have clearly seen the relays are Omron G5T-1A. SPST 5A 250V AC.

I wonder how many I2C relay boards you've ignored...

http://www.robotshop.com/en/8-relay-add-on-unipi.html?gclid=CjwKCAjwssvPBRBBEiwASFoVd9Yd3XgFJ5IHqgyWijOn4egQrfl2bRbUtkNqR1SVZ7KIpJOaHebMFhoCmEgQAvD_BwE

avr_fred:
Your basic observational powers are severely lacking... it's a custom board with a very nice photo that had you spent 5 seconds observing said photo you could have clearly seen the relays are Omron G5T-1A. SPST 5A 250V AC.

I wonder how many I2C relay boards you've ignored...

It looks like a nice board; I didn't research the relays, but did see the terminal strips.

8-channel relay board for Raspberry Pi and Arduino from Peter Jakab on Tindie
8-Channel Relay Driver Shield | Freetronics
http://www.robotshop.com/en/8-relay-add-on-unipi.html?gclid=CjwKCAjwssvPBRBBEiwASFoVd9Yd3XgFJ5IHqgyWijOn4egQrfl2bRbUtkNqR1SVZ7KIpJOaHebMFhoCmEgQAvD_BwE

The first is Peter Jacobs of London; I wrote him Wed or Thursday via Tindie but have not heard back. The second I'd seen, but is a form factor unsuitable for this job. The third looks interesting. It is single power supply vs. many others that allow a separate relay supply. And it's not yet available.

If you know of others, please let me know.

So you have found boards, they're either not acceptable or available. Got it.

So it appears your specs don't align with the market choices. Time to think outside the box? Perhaps go half custom and address the difficult portion of your needs, I2C.

Find a suitable parallel input relay board. Then, build a small custom board with a MCP23017 to convert I2C to parallel such that it mounts on the relay board header. You could have these designed (if you're not able) and built at nominal cost if you're building any quantity.

If you want din-rail mounting, have a look at Phoenix Contact, they build a full range of mounting clips and pic board holders.

Yes, DIN is good and know about Phoenix Connect.

Now considering
PCF8574-I2C-Bidirectional-I-O-Expander-Relay-Control-SmartHome-Ardiuno-Raspberry https://www.ebay.com/itm/282692860765 & 8-Eight-Channel-5V-Relay-Module-Board-with-Optocoupler-Power-Supply-PIC-ARM https://www.ebay.com/itm/322834065204

It looks like a straight IDC cable would connect the two boards. But that’s 2 boards to mount per bank, and not keen on depending on eBay as a supply channel.

That seller would never see my money... but that's just me. Here's a similar model from a more reputable seller. Reasonable shipping too, especially with a 10pc order.

https://www.ebay.com/itm/PCF8574-IO-Expansion-Board-I-O-Expander-I2C-Bus-Development-board/351875821618?hash=item51ed6ef032:m:mRxQbdJsdU7r1HQPlvNq_QA

The #1 issue issue with FleaBay; it’s a crap shoot re: venders. I risked $5 on the first one, and also got a mix of relay boards from several places. The one is 24V but it’s screw term not IDC headers.

Can’t tell the spacing of the 10 pin headers until they arrive, then seek an IDC cable. Have to find a 4-pin I2C female connector as well.

Just looked for DIN clips; prices from “gulp” to insane. Phoenix is mostly the latter.

The board I offer uses Phoenix brand (Made in Germany) screw terminals, the same 3.5mm pitch terminals I use on the Mega and Uno screw shields I offer.
The Terminal strips are 0.1" pitch for connecting the control signals from an Arduino and then daisychaining to subsequent boards.
Power for the relay coils is passed along thru the DC power blocks, or optionally thru screw terminals as well.

avr_fred:
That seller would never see my money... but that's just me. Here's a similar model from a more reputable seller. Reasonable shipping too, especially with a 10pc order.

https://www.ebay.com/itm/PCF8574-IO-Expansion-Board-I-O-Expander-I2C-Bus-Development-board/351875821618?hash=item51ed6ef032:m:mRxQbdJsdU7r1HQPlvNq_QA

Hopefully they will stack like railroad cars as we may have 8 of them. (Or eventually 16)
Wish vendors would include dimensions.

Lacking any clips that {unknown} width may have to make a /_________\ slot in a bar of some plastic to slide them in from the end; then DIN-clip the bar to the rails.

As usual, the "Better, Cheaper, Faster; choose any two" rule applies...

On relay output boards, I can find 8-port relay boards. Great.

But I want ones with header pin so I can just plug a IDC cable in.
There are a few like that:
https://www.ebay.com/itm/322834065204for example.

But I want 24VDC relays, not 5/12V. They exist, but it appears only with screw terminals.
And I want DIN rail mounting, but.....

And it's unclear if the various units have or lack LED's on each relay channel.

Gnash....

Once and done project or on-going? How many total boards do you need?

You can populate my board with 5A, 24V coil SPST relays
https://www.digikey.com/product-detail/en/omron-electronics-inc-emc-div/G5NB-1A-E-DC24/Z2773-ND/1731473

The TPIC6C595 shift register that sinks the coil current can handle that no problem, it's rated to 33V.
I've designed in an LED indicator per channel, and can customize the board size if you can define what it is you want. Right now it's 50x80mm.

If you want IDC, I can even add that too, altho that usually implies 2x3 or 2x5 or 2x8 or whatever length header and smaller 28 gage 0.05" spaced ribbon cable. What kind of currents are you switching?

http://www.king-cart.com/phoenixent/category=RECEPTACLES-SOCKETS+IDC+.1SP+%26+2MM+SP
http://www.king-cart.com/phoenixent/category=WIRE+%26+CABLE+-+BULK

Not one-off, we're building them into a product, but it's low volume.
This unit will require 4, future units more or fewer.

(BTW, another gripe about the descriptions is it's not always clear if the control lines are active low or active high. I was excited about http://www.dx.com/p/arduino-compatible-8-channel-24v-relay-module-expansion-board-145731 but that's not clear, and of course, it's out of stock.)