EEPROM variable resetting after power loss

[otrotabi]

I have just received a TM172PDG18S which has been working well so far for a couple of years.  I am asking this question before I connect it to my laptop, in case anyone has a suggestion before I do and eventually start changing anything.

The customer complained that the set-point went back to zero after a power loss so I powered it on, changed the set-point, powered off and after powering back on it turned out to be true, set-point went back to zero.

I changed a couple of other EEPROM variables and the new values were held after powering back on.

So my question is: is it possible that some memory positions in EEPROM can get damaged ? Or what else maybe the issue ?

[M_Cervati · Accepted solution]

Hi,

eeprom location writing is performed by BIOS and there is a procedure to avoid unuseful writings, in fact if value to write is already the actual value it is not written. So I don't think the number of writings is over the maximum number of writings (worste case 100K). To write eeprom parametr are you using sysWritePadXXXX function block? If yes, are you checking the return value of this FB after execution?

Other possibility is from modbus channel. TM172 is master of a modbus network? If yes in the variables to write and read is there also the setpoint? If yes, the writing should be enabled after reading the parameter otherwise at start up setpoint not yet read is 0 and the modbus write overwrite the last value. So the best behaviour is disable writes at start up, read the modbus varaible, check if node is present and valid and then enable the modbus writes. 

Let me know.

Marco

[otrotabi]

Hi Marco and thanks for your support. 

Eeprom parameters are changed with the embedded display and not by a function block.

There´s no modbus communication but there´s a Can Bus communication. Maybe that is the issue. I am going to check and let you know.

Regards