Data storage in case of power failure

Hi Guys.

I'm using a Logo 0BA8 with RTD card and TP177 6"HMI.

Using the network analog input, I enter a temperature value to be compared with a PT100 to switch on a motor. The program is ok, it's working. But, now I'm thinking about possible power failure. The parameters cannot be lost, so I need to save/store it.

What is the best way to do it? And how to do it? What I need is that in case of a power failure the Logo! system starts working again with the last parameters entered in the IOField.

Is there a way to do it in the software(ladder)? Or should it be done witht the DataLog block? Or maybe in the HMI?

Thanks for your attention! Regards!

ixo65

If you link the setpoint using an analog network input, you will not be able to save the value because you are using only the VM memory. And the VM memory is not retentive.
You must pass the setpoint to a parameter of a mathematical instruction by using parameter VM mapping.
If the parameters of a mathematical instruction are written directly, the values would be stored in a flash memory of the LOGO!. The flash memory is retentive.

 Hi ixo65. Ok understood about VM memory. Could you give me a simple example of how to pass the setpoint through the mathematical instruction? I’ve alteady tried something with it but without success (I’ve read something in the forum about it). 

Thanks. 

ixo65

Where should the setpoint be passed on? As a parameter for an analog threshold switch?
Which software for visualization do you have (exact version)?

Perhaps enough as a statement but already this FAQ from Siemens:

How can you configure references between blocks in LOGO! 8?

If not, then you have to give more details (also concerning the LOGO!).

 Hi ixo65

logosoft comfort 8.1 and tia portal v14.1

I’m reading a pt100 from rtd card. Showing this value on hmi tp177. It’s VM0. I have a iofield to set a temperature setpoint  I want the motor to switch on, for example, 10 degrees the motor switches on. To send this information to the logo I’m using VM2 and network analog input (because this is set on hmi). The program is working ok. BUT I’m case of a power failure the temperature can’t go to zero it must hold the setpoint value adjusted before. I just don’t know how to make this last setpoint adjusted retentive on Logo. Should I write it back on vm2?! But how to do it without making a confusion in the program I created?

Does this information help?!

thanks.  PS: I use ladder language for logo. 

ixo65

 

EduardoFS

logosoft comfort 8.1 and tia portal v14.1

I’m reading a pt100 from rtd card. Showing this value on hmi tp177.

Are you sure that you can edit a TP177 with TIA-Portal V14 SP1? 

Yes. I’m using tia portal v14 sp1. Unfortunately I’m accessing the forum with my cellphone so I cant upload my program right now :/ sorry. If you send me an example this would be very helpful.