KongFah

Mitsubishi PLC ERROR

4 posts in this topic

My Fx3u-48 M suddenly have error.Red LED error light up and all output LED not light up.Sometime,the red LED error not light up and the output LED return to normal cobdition.In Mitsubishi GOT ,have error message“Communication error ,Refer to System Alarm in Utility Menu."

Where is Utility Menu?What wrong my PLC and what i should do?

IMG_20200115_171424.jpg

IMG_20200115_171447.jpg

Share this post


Link to post
Share on other sites

Dear KongFah,

By the information you gave, it seems that your PLC is facing intermittent hardware problems. 

When the FX2N ERROR LED is lit solid it is likely to be internal hardware problem or watchdog timer - WDT - error (when the software is trapped somewhere in its execution).

If the machine is operating already for a long time and nobody touched the PLC program, the is a low probability that it is related to PLC program issue that is causing WDT error.

Another thing that points towards a hardware problem is the message in the HMI: it seems that your HMI is losing communication with PLC at some point. This may happen because the PLC hardware is failing to respond to HMI serial communication.

This "Utility Menu" in HMI is an internal HMI screen like the Control Panel in Windows. Depending on the HMI model it may be accessed by pressing and holding the upper left corner (or the two superior corners at the same time) of the touch screen for some seconds - this is the factory setting. If this procedure doesn't work, it may be that who programmed the HMI changed or disabled the settings for accessing the Utility Menu.

Nevertheless, I recommend to check if the 24V PLC internal power supply is being used to supply power to sensors etc and, if so, check if is there any intermittent short circuit that may cause PLC to go down. In negative case, consider replacing your PLC by a newer model such as FX3U or FX5U (because FX2N is not produced anymore).

Regards,

Thiago

1 person likes this

Share this post


Link to post
Share on other sites

Dear Thiago, 

 Thanks for your advice.My PLC is FX3U-40M.The PLC program is locked with password.The PLC has EEPROM  cassestte.Can i buy a new PLC and just insert the previous PLC EEPROM?Can this work?

Share this post


Link to post
Share on other sites

    Dear KongFah,

    Unfortunately, the FX2N cassete is different from FX3U cassete, so despite the password issue you cannot install the FX2N cassete in a FX3U CPU.... :-(

    Regards,

    Thiago

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now