Siemes CPU advice

[panic mode]

Hi everyone, I'm trying to get things sorted out with Siemens S7-300 series CPUs and I'm not sure our distributor understands me. They claim that 317 is "better at doing motion" and that 317 is the only PCU that does motion. (?) To me these two statements don't nececarily say same thing. I need to control simple and small machine that will have 2 servo axis for now but in the final version it might have up to 6 (all Sinamics S120). This is supposed to be compact and light weight. Yet they (customer) want me to use S7-315F safety PLC (so far only two E-Stop buttons and two interlocks) and if this PLC cannot do both safety and motion, option is to use 315F for safety and 317T for motion. I know that motion and safety are both priority tasks and as such they are resource hungry. If it was for me I would be just using VFD drives and standard CPU. All I need to do is set speed, target position and tell it when to start. I don't need to do anything fancy that requires coordinated motion, virtual axes, axes follower etc. Any opinions? It's new for to do such things on Siemens and I have feeling that this will be huge overkill. Do I really need two CPUs for this given that motion is going to be so simple and total number of I/O is going to be only some 32 points?

[Groo]

I presume they mean its the best as its the only one with a built in controller. The doc below may give more info: CPU 317T-2 DP: Controlling a SINAMICS S120 Edition: 12/2005 Getting Started Drawing number: A5E00480391-01 can be found at http://support.automation.siemens.com/WW/l...amp;treeLang=en also info at http://www2.automation.siemens.com/simatic...b-cpus7-317.htm I would expect that you could program servo control into the 315 using function modules like FM 351 or FM 353 cards. Just a quickie question, as a mainly Siemens programmer (Modicon and AB as well but usually Siemens) and someone looking to go to Canada as a skilled worker, how popular is Siemens in there? I plan to give it a go, even though I've been told its difficult for a non Canadian to get work.

[panic mode]

Well i'm not too sure, they do seam to have buildings on every corner. At the moment we do about 50% AB, 25% Mitsubishi, 20% Omron and 5% Siemens. Three years ago we did 0% Siemens but it looks like it will be 25% by the end of the year. They seam to be moving in very fast, they have changed distribution network etc. We have seen couple of our customer switch to Siemens in last two years. Siemens used to have lots of little distributors, but then they switched to only one (Ontor). Ontor had to drop all other brands of course but I don't think they regret it. They are still looking for skilled people to fill some gaps (like support on products I was asking about). Right now I'm working with them as well as Siemens directly to get the right solution for our new customer (also fresh to Siemens). I don't know if this is global trend here or just my observation but if this info benefits you, I expect nice cold beer, and if not, you never heard from me. I don't know which part of Canada you are interested in, but if you come to GTA, feel free to contact me.

[Groo]

Thanks for the info, sounds promising. I've applied for a couple of jobs this week, one in Toronto the other in Barrie but I don't expect any success unless I'm in Canada. I originally looked at Vancouver (my wifes main choice as she's Japanese and it would be closer to home), but there doesn't seem that there's a lot of industry there. Ontario looks more promising, Alberta is booming but I haven't done much oil and gas, mainly food industry and associated packaging equipment or conveyong systems. Worked in Montreal for 10 months loved it but can't speak French. At the end of my current project I'm planning to take a 6 month holiday in an attempt to get an offer the for HRDC validation, so never know I might be in the position to buy you beer next year.

[JesperMP]

Hi Panic. The only reason why one would choose an F-PLC to take care of the safety of a project, is if the flexibility of the PLC is important enough to make an advantage as compared with a "traditional" solution . So there is no absolute requirement that you choose an F-PLC. Another comment is that there is also a 315-T. If the 317-T is too expensive, then maybe the 315-T could be the solution. I cannot estimate if you need a dedicated motion controller or PLC with integrated motion functions, or if a regular PLC is enough. I think you have to consult someone that is very experienced in motion. Some people in my company has made motion solutions with a regular PLC. However, it was not a highspeed motion application.

[panic mode]

I know that F's can do safety but I was hoping they could still do other things (a lot of other things, everything standard CPU would be able to do). Even little brick style PLCs can control an axis or two, but I still can't find any info on number of servo axis that 315 would normally be able to control. Project leader came this morning, it seams that money is not an issue (I like to spend it all) but now customer is having second toughts - not about money but about motors (it's hazardous location).

[JesperMP]

The F functionality is an addition to the standard functionality. So yes, an F CPU can do everything a standard CPU can do.However, an F CPu does not have the "Technological" functions that a T CPU has. With only 3 safety circuits, I think that an F CPU is not important for you.