A sensor with digital output will only give you information whether the pressure is below or above given threshold. You can connect it to digital input of UniPi. You have to decide whether this is sufficient for your project or not.

Jaroslav

Did you edit the /etc/owfs.conf file? It should contain the following:

!server: server = 127.0.0.1:4304
allow_other
server: port = 127.0.0.1:4304
server: i2c=ALL:ALL
timeout_volatile = 2

You will need to restart owserver for these settings to have effect. Or reboot the Raspberry Pi.

Can you post here the output of the owdir command? Please start with only 1 expansion module.

Jaroslav

For sure this is possible, it is called a distributed control system. The software will be more complex (e.g. you must handle network communication problems correctly) but you will not have a single point of failure. When the Local Control Unit looses connection with the Master Control Unit, it will still work locally, you can even define an emergency or fail-safe mode.

The master control unit needs no I/O, it can be a plain Raspberry Pi. Or you can use 1 master/local unit and 4 local units.

For communication, I would use Modbus TCP.

Jaroslav

Probably too late for the party but still I'd like to mention that this is possible with REX Control System.

Jaroslav

Hi Merv,
depends on what "large" means for you. If 10=large then we did: http://unipi.technology/customer-reference-unipi-likes-rex-controls/

Your project is very nice, looking forward to hearing more about it!

Jaroslav

Well done! Still I'd like to know why it was not working with your previous setup. Any ideas, Tomas?

Apart from the micro USB power supply, which is not necessary, I do not see anything suspicious.

I'm out of ideas Any hints, Tomas?

Previous conversation with Martijn also revealed that he uses 10 cm cable which was provided with the board.

Martijn: did you try connecting only one extension board? Can you please post here the output of i2cdetect with a) plain UniPi board and b) with the 0x22 extension board attached?

And just to make sure: Are you able to control the onboard relays?

@adz996:28fty4kx:

I will use an Omron encoder and max revs will equate to 216khz at 12-24v.
What do you think, possible to be read by the pi through the unipi digital input?

I do not believe this is possible. Note that the inputs are evaluated by the Raspberry Pi CPU so processing the encoder pulses will compete with all other tasks in the operating system, resulting in loosing pulses. Plus the optocouplers on the inputs are not able to pass through such high frequencies. My recommendation is still the same: Use microcontroller or specialized I/O hardware for this purpose.

@adz996:nycd5am3:

I need to use a rotary encoder through one of the digital inputs.

How many pulses per second does the encoder generate at maximum speed? In general, I do not recommend using Raspberry Pi GPIO for reading encoder pulses. Use microcontroller or specialized hardware for this purpose. IMHO a rotary encoder typically uses 2 signals…

@adz996:nycd5am3:

Is the Unipi PNP or NPN collector type input?

PNP, you have to supply voltage to the input.

@adz996:nycd5am3:

I know development takes time, as I am doing the same but a detailed (Mitsubishi level of information) specification sheet saves time and adds desire and credibility.

Your comment should be targeted somewhere else. Please note that I am neither a developer nor employee of UniPi.