iMX233-OLinuXino based dream PLC

[Stinde]

The problem using present UEXT IO modules is they need CE approval in commercial assembly, using 230V relays.
To avoid expensive approval, IO module could have open collector circuit to drive external relays. For example RT relay with DIN rail socket are both approved and cost <10€.

Instead onboard relays, I would like to have more analog inputs and maybe more than 10bits resolution. Onboard circuitry or option for various type temperature sensors would be nice.

Timo

[jeroends]

for more analog inputs you could use ie. a max127: 8 channel 12bit 0/5 -5/5 0/10 or -10/10V input A/D with a few external components. ideal for measuring industrial signals.

[cKon]

Ideal Analog Industrial signals are Inputs selectable for 0-20mA, 4-20mA,0-10V,RTD, ThermoCouple
and Outputs programmable for 0-20mA, 4-20mA,0-10V.Are there UEXT modules for the same? , or are there any third party boards compatible ( low cost ,low speed 10/12 bit resoultion) . I am already working on the software side ,this is the only feature missing,after which i will buy my maxi and work on porting the software.

I have found this interesting http://www.analog.com/en/content/cu_eb_plc_demo_system/fca.html How ever its rs-232 based , would appreciate some inputs.

[Stinde]

Hi,

CamdenBoss CNMB6 DIN rail box PCB B (middle) size is 57x102mm. Olinuxino iMX233 MaxiPCB size 54.6x96mm. You could fit Olinuxino into the box adding some empty area around OLinuXino Maxi PCB and using UEXT and GPIO connectors facing up.
http://docs-europe.electrocomponents.com/webdocs/105b/0900766b8105ba74.pdf
The height of the USB connector might be problem.

The downstars of the box (PCB A) could be used for IO board with terminal connectors.

Timo

[veseo]

Hi,

that's a nice idea. Actually module that has both male and female UEXT connector, like MOD-IO, doesn't are really pass-trough because extend UEXT only partially. For example MOD-IO extend only the I2C to bridge multiple IOs.

I will solve building custom IDC10 cable (one female two male), because I need both SPI and I2C for two different modules, but having a direct extension of UEXT make things easy.

May I give one suggestion, now in the Industrial Automation there is the concept of intellingent junction box, extend field cables is a costly and annoying matter, so many companies (like the one where I work for) is selling modules that move the electronics directly in the junction box and then connect it via ethernet or RS485 to a main controller.

This is just an extreme concept of distributed system that can easily apply also for home automation, where is not so confortable to have a central PLC and run cables over the home. You have yet the hardware, the MOD-IO, just need a more powerfull microcontroller to handle an UEXT communication module. May I suggest an AVR one, to get in touch also with the Arduino community.

So your architecture will be the OLinuXino as central controller that may be extended via IDC10 calbe or via ethernet/wireless UEXT module to their remote I/O. On the deterministic (real-time) point of view, with Ethernet is no longer a problem.

Then there will be the certifications, CE is not enough in Industrial Automation because needed certification very on the plant type, but certification cost money and to keep the price lower these cannot be offered. But this type of PLC or distributed IO may be applied in a lot of not industrial cases.

Regards,
Dario.

[farlane]

For some reason i dont have much faith in using I2C/SPI as a 'backplane' bus. Theyre not really meant for this kind of application, going off PCB. Multiple times i have seen I2C busses lock up because of some sort of device borking and keeping the clock line stuck.

Would'nt a more 'industrial' bus like CAN be a more sensible choice?