Need help to use Mitsubishi PLC FX3U using RTC

[cmorales 0]

Hi I'm trying to find a funtion to program PLC FX3U, need to control lunch breaks on 2 work shifts. I looked programing manual, and did test using time compare function and it worked, but there are like 15 set of times that need to trigger a ringing bell. I hope you can give me a clue on this request. Regards

[Ron_S 61]

Although it can quite easily be done with an FX3U, in my experience they are not much use for work shift break times. Unless you have a method of regularly updating the exact time from a server or manually entering the exact time. Why? - the FX clock drifts horribly and if the workers breaks are starting later/earlier every day it soon causes uproar. I have done exact time functions for things like blowing down the air before a shift starts to clear water from the air lines and unchecked the times were out by nearly an hour within one year. You can buy dedicated shift buzzer time-clocks and they are very accurate and once programmed need to more attention or alterations.

[cmorales 0]

Thanks Sparky, you're right Our system just broke and I was trying to help by using a spare plc that we use for machines.