Kirk Wallace wrote: > On Sat, 2008-03-01 at 20:09 +0000, Chris Morley wrote: >> Greetings all: > ... snip >> Also I would like to know from users where the documentation is >> lacking/unclear. >> >> Thanks >> Chris Morley > > I am still having trouble understanding the scope of EMC/Classic Ladder. > It would be nice to have an introduction presenting why someone that > knows nothing about EMC/CL might want to learn more about it. > > So far, my understanding is that CL provides a ladder programming > language with HAL links such that procedures can be expressed in ladder > language form and linked to EMC IO. So CL has two roles. One as a > scripting language, the other, as a software PLC. It seems the Mazak > tool changer is an example is of this. > > One element of confusion, is the role of the Modbus feature. I get the > impression that Modbus is usually used to communicate with hardware > PLC's. What is the nature of that communication? > > Would it be more appropriate to separate the scripting language from the > PLC? >
I don't think of CL as a scripting language at all. It is strictly a software based PLC. The original ClassicLadder was non-realtime, and had built in drivers for a small variety of I/O devices, including Modbus. Porting to EMC made it work in realtime. The port also lets ladder programs use any I/O device that has a HAL driver. In fact, it lets CL interact with any HAL signal, not just I/O devices. If needed, a ladder program can be used to perform some logic on signals from EMC and send the results back to EMC without ever going outside the PC. When CL was ported, its original drivers, including the modbus driver, were replaced with hooks into HAL. So the modbus driver did not get ported. Regards, John Kasunich ------------------------------------------------------------------------- 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
