Micrologix time of day

Which version of Micrologix? I don't believe the 1000 has a real-time clock (RTC), the others do. Is there some sort of HMI attached that has a clock and could write to Micro?

Real time Clock models have that capablility, but if you are using an older model, You would have to program in a Time Clock manually, and hope for no power losses.

I once did this for a sprinkler system, worked well, until we lost power.

Some of the ML100x's had a RTC module that could be purchased seperately as an add-on to the processor. Not sure which ML that you have, there are ML1000,1200,1100 and 1500.

You can use the Status bits for this if your PLC has a Real Time Clock.

On a Micrologix 1100, S:40 is hour, S:41 is minutes and S:42 is seconds.

You just need a few integers to store your setpoints and compare to these registers (EQU).

For example:

EQU S:40 N7:0 EQU S:41 N7:1 EQU S:42 N7:2 OTE O:0/0

Where N7:0 N7:1 & N7:2 are the first setpoint hr&min&sec. This would energize the output for 1 second each day.

Hope that helps!

Most of our Micrologix are 1000's, I believe this one is also. I have a 1200 available, if that would be a better choice. No HMI for this application. I'm not really familiar with status bits, but I'll study the example and try to make sense of it.

The RTC on a ML1200 is optional, see below

Unfortunately, the ML1000 does not have a RTC, so you'd have to program the clock yourself as someone already suggested. I did this in college once using the 60hz from the AC power. Turns out the power company corrects the Hz every few hours and results in an accurate clock. However, if you lose power your clock will lose time so I would avoid this approach, and just upgrade to a PLC with RTC.