Lots of relays

Hi. I am currently building a pool automation project. Been on it for a while, but i have run out of GPIO pins to trigger relays once i have connected all my other sensors. I have a couple of OI PI Plus I2C GPIO expansion boards that i wish to use. Each one has 36 IO pins, so i will only need one of these and I will connect all of my relays to it. the GPIO pins on my PI3 will be for mostly inputs then. My question is, How do I make this work in OpenHAB? there is code that i can find to make it work in Rasbian, but not OH. I haven’t found anything that really documents it on the forum, hence the post. Any help would be appreciated. https://www.abelectronics.co.uk/p/54/io-pi-plus
here is the link for the ex pander for reference.

I have written a very basic program in Python to make a link between RPi gpio pins and MQTT. I have plans to make it expandable to allow installing only the modules desired, and adding a module to support I2C I/O expanders. If you aren’t in a big rush I was going to make the new modular version available on github.

The board seems to be based on the MCP23017 chip. There is a MCP23017 binding, maybe that can work.

Thanks for the great info. i will solder up the header pins when my new soldering iron arrives ans start playing.on another note, i looking at controlling an access panel on the spill way pit. I have 2 DC linear actuators that lift the entire panel and the another two that bring it forward. writing the code for this in basic terms would relay 1 for up, 2 for out. 3 for in and 4 for down. they all have there own limit switches, so running them for an extra 60 sec wouldn’t harm them. But what i cant find on the forum is how this can be controlled from something like the roller shutter item. for example, press up. This executes a script for Gpio 21 to go high that triggers relay one to go on, after 50sec it turns off then GPIO 21 goes high for 40sec turning relay 2 on, etc. It can be done with a simple switch, on = up and off = down. is there a better way that i"m not seeing?