Siemens PLC won't auto-run after power-up

Lamboom

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Mar 2014
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Fallbrook, Ca
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It was all working great .. for a while. Every time I turned on the system (PLC, HMI, ethernet switch) .. everything would go "green" and it all worked fine. Then, just for training, I added good stuff like delays, and a math function, and a few more goodies on the HMI.

When connected to the PC (TIA) during programming … everything loaded.."green board" all around .. (always checked the little box for auto run at startup).

HMI worked great, PLC worked great.. everything functioned as expected. The PLC responded to the HMI buttons. Then I added a nice new I/O Module. Didn't use it in any program yet… Just connected it to the PLC. On power-up .. the module indicated a flashing green LED. Focused on the module, hit "download" .. and after TIA loaded some spurious stuff, which didn't make much sense, the modules LED went green … Great!

Everything working (green) so, I tested all equipment.. and everything worked great. then shut it all off (Master Power) .. and .. turned it back on, expecting all to initialize back to green, PLC to "auto-run". But, Nooooo Not the PLC. (everything else was up and working fine).

I had to go back on line, and initiate PLC "Run" mode the hard way .. along the way.. the TIA tells me my PLC is "Not the PLC I'm looking for" .. (the one I'm trying to "run" is not the one in the program) DUH …

I don't care…I say, go online, launch it anyway. TIA does, and all is well ..green lights everywhere…working fine. It's apparent, I can never turn the system off… sigh!

TIA Portal is V11 SP2 #5 Upgrade

PLC is S7 1200 ...1212C (6ES7-212-1BD30-0XB0) Firmware 2.02 (can't go any higher than 2.2 ..without exploding)

HMI is KTP 600 Basic PN (6AV6647-0AD11-3AX0)

I/O Module SM 1223 (8)24DC in/(8)24DC out (6ES7223-1BH32-0XB0) .. yes … it's 2 years newer than the PLC.. but Siemens says it's compatible with this TIA & PLC … but, nothing is connected to it yet.. nor is anything in the program.. yet.
Any Idea what's preventing the PLC from "Auto Run at Startup" … ? (remember, I always check that little box during downloads)

Thanks… Regards, Michael
 
The first thing I would recommend is to see what the diagnostic buffer says. You can see this when you go to Online and Diagnostics. It should have an entry for poweron, another for startup, and it should tell you what it tried to do from there, and if it had any errors.

One other thing to watch out for is a setting in the device configuration that controls startup behavior. The default option is not to always go into run. I can't recall what it is off the top of my head, and I don't have portal In front of me right now. I'll try to remember to check tomorrow.
 
Thank you MK42! That sounds brilliant. I may have forgotten to set the configuration parameters properly.. I'll check. Thanks for the info on checking online diagnostics .. I shoulda thought of that. (still a newbie here) ... got too caught up in the possible conflict between a new signal Module and an old PLC (version 2.01) Thanks again, Regards, Michael PS: I'll get back to you with the results...
 
About halfway down the PLC device properties there is an entry for "Startup". The first setting is "Startup after POWER ON", and you probably want it set to "Warm restart - RUN". This is the setting what people want 9 times out of 10, but it is not the default.

My guess is it's the lawyers fault, in case a machine shut down with an issue then started back up and hurt someone. This way someone needs to CHOOSE to take the less safe option. Blah liability blah... You make a PLC without a run switch, it needs to start in run.
 
Yup.. Indeed... I thought I had set that to "Warm & Fuzzy - RUN" ... In fact, I had done it many times on earlier projects .. The default now is something like "Download & Just Sit There" .. I had totally mised it, and got too involved in a possible conflict with the New I/O Module & Old PLC.

Also.. some of those "Earlier" programs weren't set for Warm & Run... and, but, they "auto ran" anyway ... kinda fooled me... Thanks again... Michael
 

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