Netduino PLC

Hey!!! I want to realise a PLC with the Netduino Plus. The PLC should have the following features: Programmeble over Ethernet Digital I/O Analog I/O Port for Extention I was thinking about a software that reads a code file from the SD card and then executes the code. The PLC should also listen to Webrequests so you could control it with your smartphone. I already wrote the code to transfer a file to the SD card over Ethernet. So I only hav to add a kind of Code interpreter. If someone is interrested in this, please contact me and i will send you the codefiles, so that we can develop together. I hope there is some who is interrested in this Project. Greets, poschi

Howdy, I am also interested in using the Netduino as a PLC. It sounds like you have done some work on downloading files to the SD in preparation for downloading code for PLC to run. Beyond that it seems to me you will need - A grammar to represent the functionality of the PLC (Ladder Logic is ubiquitous). A interpreter/compiler to translate the machine definition written in the grammar. An engine to run the translated machine definition. Next you need I/O... The Netduino doesn't have near enough digital I/O to make any sort of a useful PLC. So you need someway to expand the I/O that it does have. There probably are some Arduino shields that can do this with relays and such. I was thinking though you could use the I2C port which is good for up to 400KBits/s which should be plenty fast to scan a good number of I/O points. Design a standard I/O module that looks like an I2C component to the Netduino controller. Each module would be settable to a different I2C address and the I/O points would look like byte-wide registers within the component. The I2C protocol is daisy-chainable ( new word! ) so one module could connect to the next and so on. To implement the I/O modules use an inexpensive PIC controller that supports I2C in hardware. From the Netduino controller then, run the I2C SDA and SCL lines, power, gnd, a common clock signal to drive the PICs, and probably a sample synchonization signal so all the modules update at the same time. Ya know I've always wanted to try out the idea of using PICs as I2C components and will probably do this. Just gotta get more I/O into the Netduino! P.S. Interestingly, the Atmel spec sheet for this ARM7 sez it has a hardware CAN bus peripheral...

Your Ideas sound great... Maybe we can get in contact, to discuss about this in more detail. For the Expansion i also have a idea, how to realise this.