Ziemens said:
it is true that i have only worked with siemens (my member name reveals it) due to reasons such as price, delivery, support, work overload,... but i can tell you the following about the siemens product:
1. it has excellent hardware quality. mistakes made by assembly or commissioning do not easily do damage.
I find Siemens products to be far below average. We have purchased TONS of their hardware and I've never seen so many issues:
- Only rarely you get what you ordered, they feel free to change part numbers and revisions based on whatever rolls off assembly line and maintaining compatibility becomes your job.
- Only this year I have some 50 motor modules (S120) which had issues with - safety integrated.
- I've had several 3TK2830 safety relays that have broken base (way too flimsy, often snaps during installing, not to mention attempts to remove it from DIN rail). i didn't believe how many of them got broken so i took new one out of package, held it in my hand while trying to remove one that was already installed. it did work - once, but it took much effort and care and even then it was obvious that unit was used before.
- bunch of the same safety relays had failed and had to be replaced because one or more contacts didn't operate correctly (move with the rest as expected from safety component)
- PN Connectivity Boxes for Mobile HMIs had failures (safety circuit).
- One of the Mobile HMIs came password protected.
- Another (same) HMI would not communicate on any of the comm ports (replaced)
- another HMI (all same model) was working fine for few days. it was repeat job so all it's left is setup and calibration (takes few days) so i didn't bother bringing laptop to the shop (tool was not connected to our network) since everything i needed was on HMI. i had to login as programmer to access all features but this is normal procedure. after setup was done, tool was run through it's paces it was time for acceptance test. customer shows up and we start checking things itme by item following long list. eventually i had to demonstrate security (it was built in feature, not DIY password protection) and I did, well at least i tried. all accounts worked as expected but Programmer which seamed to have same rights as Operator (login was accepted but access to specific features was blocked).
- the ET200S modules have key that snaps into base when module is inserted. Removing it requires non-existent 10-prong tool, Siemens suggests prying it out using simple flat screwdriver which bends the prongs and damages unit.
- We had servo motor that got burned (literally turned to charcoal). Motor was sized and installed according to Siemens guidelines, load and duty cycle was never exceeded. Siemens reviewed whole thing before it was built and few times later on (every time that motor ended up in smoke). They never admited what was the problem or why built in temperature sensor never did it's job.
- working on project whole day (test, make change, save download) eventually leads to corrupted MMC. The documented procedures and suggestions from tech support didn't work (well replacing MMCs worked but I soon run out of spare MMCs) and they had no clue how to restore the corrupt cards to factory defaults without using promer (not the handiest little gadget that one can cary around).
- changing one of the safety files and downloading to controller should cause fault because integrity of safety program is gone. i decided to test it so i explained my intend to colegues and purposely changed one rung (changed contact from NO to NC), saved file and downloaded it to PLC.
change was accepted and program worked according to code change and without recompiling whole safety code. i tried cycling power and everything worked again. we cycled power homed machine run few cycles no problem. i was shocked so I went to try it out on another machine (different kind but with same processor). i repeated whole thing and it worked the same way. two days later (after several power cycles and process sequences) one of the two showed fault on powerup. i went online to check diagnostic and it complained about inconsistency of the safety code. compiled project and downloaded it, everything worked. why it took two days for it to figure out that safety code is not sharing same checksum?
and i don't want to even mention software quality or the poor website. even mighty Google only finds scraps at best, this is clear indication of very poor web presence.
2. software is not very user friendly, but it can do all that you want and more.
yes, often one has to bend backwards just to do simple things.
3. they have all objects that contain electrons. so you can do all the automation compatible with all electrical hardware.
i don't know how to interpret this statement, i guess must be typo. i've never seen products that use only protons and neutrons as building material.
4. new products are usually hard to commission for the first time (manuals contain hundreds of pages...), but once it started you do not have to worry about them again.
well, in my case manuals started showing up on Siemens website months after we purchased hardware. manuals are incomplete, lack basic revision control (same file name, same document number, same title, same date, same link it was downloaded from, but files differ by hundreds of pages). did they ever hear about ISO?
5. their prices are competitive, maybe due to some of the above problems
hardware price is small part of the cost and plays big role only if used on standard product (big quantity). engineering time is bigger portion on any but maybe trivial project. their software lacks basic features such as import and export, copy and paste etc. or have limited scope.
good support can easily offset many product deficiencies (hardware or software). support in Ontario is horrible. they have done so little it's not worth mentioning. in some cases they flatly have refused to even look into issue or have requested to hand them over whole project the issue was undocumented error code in NetPro, all they have to do it have someone look it up in their own source code. i offered them to come and check it out on our site using one of our laptops or me to do any troubleshooting step they want for them. they refused, whole project or nothing. maybe i should just give them the project and have myself fired and sued by my own company.
in the end i offered to do them a favour and search through their source code for them but for some strange reason they refused, wonder why...
