Ok I was able to see it. 

I'm curious, does PLCSIM recognize the CPU startup configuration?

Did you have it configured for warm re-start or no-restart (stay in stop mode)?  

Kal.A

Ok I was able to see it. 

I'm curious, does PLCSIM recognize the CPU startup configuration?

Did you have it configured for warm re-start or no-restart (stay in stop mode)?  

Hello.

I was not sure, so I had to test it.

.. I have never played around with the 'power' button on the simulation before. I can confirm after the test that the start-up behaviour is the same as what you set in the hardware configuration.

Thanks qwazee. One last test to clear up the issue with non retained tags.

Let's say the CPU is configured for warm restart and you download changes to other dbs or program cjhanges, do the non retained tags hold their values on restart? They should.

Kal.A

Thanks qwazee. One last test to clear up the issue with non retained tags.

Let's say the CPU is configured for warm restart and you download changes to other dbs or program cjhanges, do the non retained tags hold their values on restart? They should.

It depends on what changes are loaded, which PLC and which firmware. My replies to date was focussed on the S7-1200 FW4.3+.

I am not going to test it. It will have to wait until you are able to do so. I am predicting that behaviour will be the same as with an actual PLC.

1. Changes that pushes the PLC to stop will effect the non-retained tags.
   
   
2. Changes that modifies the structure of the DB runs the risk of being re-initialized. That can mean ALL tags within the DB. Less chance when the memory buffer is configured. Later firmware versions are more resilient too where actual values are kept.
   

Thanks qwazee. I agree the non-retained values will be initialized on warm restart, work memory is not. 

Cheers 

Hello friends,

I almost solved all my problem. I set the RETAIN in the TON DB and it really helped.

BUT, it didn´t solved all my problem.

Well, now, with the variables of the TON with the RETAIN set, if the CPU goes off/stop and back to RUN, the program keeps running from the point it was. This is perfect.

BUT, the problem is that at the moment I press RUN in the CPU and the CPU starts running again, the program starts running, and this is not good because I need the operator to acknowledge that a POWER FAILURE hapenned and chooses to continue from the point the software stopped.

So I created a script and popup window with a button CONTINUE or STOP. So far so good. I created a logic with a OB100 to know if the power failure happened, etc. BUT with this logic I set a bit, for example MEM_Power_failure_happened, that CUTS the power of the TON with the SETPOINT TIME. This starts the problem because at the moment I cut the power from the TON it starts counting the TIME from the beginning. At this point I´d like your help my friends...how to solve it? I need to continue counting time and not RESTART counting the time.

Thanks.

There's a timer instruction TONR, R for retentive. 

The search function in the forum may give you more answers.

You realize time is going to eventually run out 

 Hello,

Yes, just a HMI button is acceptable. Any suggestions would be extremely welcome.

Thanks.

0_Einstein

I think you have a basic misunderstanding of how to properly handle a restart of the PLC, regardless of power cycle or simply stop / start.

If your process is extremely simple, sure, you can pick up right where you left off - provided nothing requires time from power on to settle out.

Also, if safety is any type of consideration, nothing is supposed to automatically power up that can cause motion without operator intervention, and an HMI pushbutton is not generally acceptable because it is software.

A physical button to reset things is generally accepted practice to enable a reset of the system and enable power to control devices like valves, and to power up drives for motor controls.

Again, if it is simple (and safe) enough, sure, just starting the plc program back up with a little operator input might be ok.

For a simple PLC data logging setup, it might be perfectly fine to just start right back up exactly where it left off.

EduardoFS

Hello friends,

I almost solved all my problem. I set the RETAIN in the TON DB and it really helped.

BUT, it didn´t solved all my problem.

Well, now, with the variables of the TON with the RETAIN set, if the CPU goes off/stop and back to RUN, the program keeps running from the point it was. This is perfect.

BUT, the problem is that at the moment I press RUN in the CPU and the CPU starts running again, the program starts running, and this is not good because I need the operator to acknowledge that a POWER FAILURE hapenned and chooses to continue from the point the software stopped.

So I created a script and popup window with a button CONTINUE or STOP. So far so good. I created a logic with a OB100 to know if the power failure happened, etc. BUT with this logic I set a bit, for example MEM_Power_failure_happened, that CUTS the power of the TON with the SETPOINT TIME. This starts the problem because at the moment I cut the power from the TON it starts counting the TIME from the beginning. At this point I´d like your help my friends...how to solve it? I need to continue counting time and not RESTART counting the time.

Thanks.

 

 Hey Kal.A,

Thanks a lot, it seems it will be perfect for my application. I couldn´t try it yet but as far as I could see, it works the same way only "accumulating" the time until RESET, is that it?

What do you meam by "You realize time is going to eventually run out"?

I´ll be working with a TIME SETPOINT, so at the moment the ET time reaches the PT I´ll go to the next step. 

Thanks.

Kal.A

There's a timer instruction TONR, R for retentive. 

The search function in the forum may give you more answers.

You realize time is going to eventually run out