C
curt wuollet
Hi Michael
Excellent and relevant points all.
For the record, no, I don't like IEC 61131-3. It seems to have created more diversity and chaos than standardization. It's an example of the rope principle: No matter how hard or which direction you push, a rope won't go where you want it to. But, it you turn around and pull, it'll follow you anywhere. And I'm a believer in standards. But, fortunately, I'm not yet subjected to software that makes it harder and more complex to instantiate logic. Most of what is done can be done in ladder and where I've been, that is the rule. No one has requested that I convert it to ST or IL or flowcharts or..... That would be the market. It's a very large part of the market, indeed many PLC vendors still don't really support anything else.
There is a large subset of what RLL tools do that is common to all, but yes, I agree that they are customized to the particular features of a given PLC. For example, some have you peek and poke registers to enable features and even call routines. Maybe those sorts of things can be abstracted into a personality module for the brand or model. That might end up being larger than the common module. The PLC tools that do that sort of thing aren't very good, because they seldom show what putting 0x04 in r1031 does, you have to look it up if it isn't your code. Volunteers could deal with the complexity that isn't economical for the companies in give away software. The biggest obstacle would be the amount of RE needed if there is no cooperation. At this stage though, I'm not ready to agree that it's not feasible, although it may not be. After all, it wasn't feasible that I would be writing this on a free *nix with free tools and that it would be displacing the works of ATT etal. What I want is ideas on how it could be done. Pick one of the fairly generic tools for the Japanese PLC manufacturers. It could look like that. My idea for solving the problem is to provide something that the PLC manufacturers might want to do. Because, like rope, we can't push them into anything.
Regards
cww
Excellent and relevant points all.
For the record, no, I don't like IEC 61131-3. It seems to have created more diversity and chaos than standardization. It's an example of the rope principle: No matter how hard or which direction you push, a rope won't go where you want it to. But, it you turn around and pull, it'll follow you anywhere. And I'm a believer in standards. But, fortunately, I'm not yet subjected to software that makes it harder and more complex to instantiate logic. Most of what is done can be done in ladder and where I've been, that is the rule. No one has requested that I convert it to ST or IL or flowcharts or..... That would be the market. It's a very large part of the market, indeed many PLC vendors still don't really support anything else.
There is a large subset of what RLL tools do that is common to all, but yes, I agree that they are customized to the particular features of a given PLC. For example, some have you peek and poke registers to enable features and even call routines. Maybe those sorts of things can be abstracted into a personality module for the brand or model. That might end up being larger than the common module. The PLC tools that do that sort of thing aren't very good, because they seldom show what putting 0x04 in r1031 does, you have to look it up if it isn't your code. Volunteers could deal with the complexity that isn't economical for the companies in give away software. The biggest obstacle would be the amount of RE needed if there is no cooperation. At this stage though, I'm not ready to agree that it's not feasible, although it may not be. After all, it wasn't feasible that I would be writing this on a free *nix with free tools and that it would be displacing the works of ATT etal. What I want is ideas on how it could be done. Pick one of the fairly generic tools for the Japanese PLC manufacturers. It could look like that. My idea for solving the problem is to provide something that the PLC manufacturers might want to do. Because, like rope, we can't push them into anything.
Regards
cww