On Mon, 2008-02-04 at 21:22 -0600, Javid Butler wrote: > Kirk- > > I have a very similar board with EIA-485 for the 40-pin PIC. It does have > complete control over the transciever.
That's good to know. > What do you want to achieve with MODBUS and how soon do you want it done? I was hoping to make Modbus a part of EMC, but as a way point, make a Modbus link to my VFD and ModIO (digital, analog, quadrature IO, Homann Designs). My time table should be fairly long since I really should be mounting encoders to my Bridgeport, but it's kind of cold out in the shop these days. > If > there is some code I'd be willing to work on porting it to the PIC, but I'm > loaded with projects right now so it will take a little time. (If it's convenient, let us know what you are up to. Do you have a website?) > It seems there > is an EMC MODBUS project forming, so maybe by the time the EMC code is > stable I'll have more time, or someone who knows the PIC will have time to > do the port. There has been some discussion that for two (three?) wire Modbus, it may not be possible to use a standard PC serial port due to a lack in transceiver direction control. I saw that RS485.com had RS232 to RS485 adapters based on PIC's, but they are expensive, so I started wondering about alternatives or if I could build one myself. At twenty to thirty-five dollars each for a PIC board with an RS485 transceiver built in, building is not necessary, but programming is. Now I'm trying to get an idea of how hard it would be to do. I suppose, I could use a PIC that is compatible with C and the libmodbus ( https://launchpad.net/libmodbus/ ) files as a model. I have an Olimex PIC-PG3 programmer and PIC-P14 (14 pin PIC) board. I may have to dust it off and play with it. > Anyway, let me know if a board would be helpful. I've got several assembled. > I've also got a board based around the 17C44 with EIA-485 as well, but none > assembled. > > Javid Thanks for the help, Javid -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
