7/8/2009 3:43 AM | |
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Hello Lalit, Great to know that Siemens products have several good points. One point I would like to add, is FC's and FB, AB does not have that either( not fully functional like Siemens). Thanks Ritu |
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7/8/2009 3:51 AM | |
Joined: 12/20/2008 Last visit: 8/12/2024 Posts: 556 Rating:
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Hi Ritu, Thanks, I forgot to mention that and I also forgot to mention that in AB you can't test the actual program as AB PLC SIM does not have all the hardware. So one need to modify the complete HW configuration in order to Simulate, and thereafter also many limitiation. Where as Siemens PLC SIM is a successful Simulation product. Thanks
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7/8/2009 5:18 AM | |
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Hey Lalit & Ritu! You guys deserve to be recruited as salesmen for Siemens! Being a Siemens graybeard, I really appreciate your posts! Keep up the good work!! Now on a serious note, many years ago I had an opportunity of working with AB products. The thing that impressed me was their documentation. Even though I had never worked with PLC/5 before, I was able to setup a system (including software installation)and produce a working programin less than90 minutes! IMO, one area Siemens can improve is documentation. We have come a long way if I compare with Siemens documentationof early 80's but stillsome way to go... Regards |
Last edited by: Phantom75 at: 7/8/2009 5:19 AM |
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7/8/2009 5:33 AM | |
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Hi Phantom, Thanks for your comments, I just started working on Siemens products and I am learner, I spend most of my time in reading the FAQ section. I have worked on AB, and I would agree with you on documentation part, I too remember when I started working on AB I picked up one SLC/500 and one manual, and I was all set to go. However in case of Siemens with one manual it is not possible I hope our Moderator will forward our feedback and direct it to Appropriate person. |
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7/8/2009 11:14 AM | |
Joined: 10/7/2005 Last visit: 9/11/2024 Posts: 3020 Rating:
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Dear all |
Last edited by: fritz at: 7/10/2009 1:37 PMEdit Data Blocks section (replaced A/B with ControlLogix) since PLC5''s were similar in memory organisation to what Db''s allow you to do in a Siemens PLC. Cheers |
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7/8/2009 3:57 PM | |
Joined: 12/20/2008 Last visit: 8/12/2024 Posts: 556 Rating:
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Hi Fritz, Completely agree on 1st point, as explained in detail. but did not very well understand your second point, Could you please elaborate in detail, it might be a good point which I am not aware of. Thanks, |
7/10/2009 2:34 PM | |
Joined: 10/7/2005 Last visit: 9/11/2024 Posts: 3020 Rating:
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No worries lalit, the majority A/B fans that I’ve met in my life don’t get it either when I try to give them valid reasons for abandoning their “toys” and start programming real PLC’s (such is the power of the dark side of the force or my inability to explain things properly). Anyway, back onto the subject and I’ll hopefully be able to make it clearer what I mean. Put simple, ControlLogix user data memory is just one big file (aka Tag database) in which you create your “tags” (well, one big global data file, every routine can also use local memory). It has all the IEC compliant features such as Arrays (3 dimensional is max though), STRUCT’s, UDT’s etc.If you need a new (global) Tag (e.g. a bit, INT, REAL or whatever) you simply create a new one (as you program), give it a symbolic name and off you go. It is indeed very similar to what you can do with the Local (TEMP) memory in an FC or FB. Sounds too easy and great doesn’t it? Well, here are things that rub me the wrong way about it: In Rockwell’s own words “In the RSLogix 5000 programming environment, data is set up in a tag database. Memory addresses are hidden from the programmer, which makes things easier for the programmer.” Call me old fashioned, but I don’t get how pure symbolic addressing makes things easier compared to being able to do either symbolic programming or address based programming (which S7 allows and you can freely switch between the two). Secondly, a half decent size program can easily have a few thousands tags in it. With Controllogix, the only distinguishing factor between each tagis their name (remember, no addresses anymore), or in other words, that Tag database easily becomes a gigantic mess as far as I’m concerned. S7 DB functionality on the other hand allows you neatly structure your user data area in two ways (inside the DB’s AND by being able to have more than one DB). Add to that the availability of M bits and Local (TEMP) data and even the program with the biggest data memory requirements can still be structured in a easy to identify format (e.g. if you look for Alarms you would give the “Alarm DB” the name “Alarms”, I think by now you get what I’m trying to explain). One last things, this thread is of course seriously Siemens biased (and so it should be, we are not really here to promote Rockwell, are we?) and there are probably features in ControlLogix 5000 that Step7 could benefit from. |
Last edited by: fritz at: 7/14/2009 3:46 PMCheers |
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7/11/2009 3:46 AM | |
Joined: 12/20/2008 Last visit: 8/12/2024 Posts: 556 Rating:
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Hi Fritz, I think some part from the above is coming inside my mind and some part is going over my mind( because of lack of experience in having practically done the above which you mentioned). Any how I appreciate I got this information and sooner I will try to implement the way you have mentioned. However I appreciate you efforts for trying to explain the things as I requested. Last but not the least I would like to comment on the below one:
I have seen several people stating the same things for either AB or Siemens. I would say it, people sometimes are reluctant to change though I might be wrong as I am a human being. But let's take the example of any one if a person is working on AB PLC. If he is experienced for 20 years in AB, how positively he tries to learn any other PLC but it will take some time for him to learn Siemens and he will always try to find AB in Siemens. And vice versa is true as well. I know there are certain things for which you can Call A/B as "toys" but the same thing people might say about "Siemens". Any how as well said> we are here to talk about Siemens and Certainly I have started finding new features in Siemens which other PLC's might not have. Thanks, I hope to ask few more questions/clarification here on this forum. |
7/11/2009 6:17 AM | |
Posts: 2661 Rating:
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Hi Lalit, That was a "profound" post! The reality is, each system is good (or bad)in it's own way. But since this isa Siemens forum and since you started the thread Excellent features of Siemens... we need to bring out positive aspects of Siemens and fritz was doing just that! My own experience with AB is extremely limited and I already stated the pros inmy earlier post. In other words I am an extremely biased pro Siemens guy who has been able to defend (and sell)Siemens to numerous Emerson, ABB, Honeywell, APACS loving customers over the years. The most common refrain Ifrequently hear against Siemens is, "It's too complicated" and my answer always is, it's structured and systematic. You have to invest time and effort to understand the system, after that it's a cakewalk. Regards |
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