Micrologix 1400 start real time clock

crawler009

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Join Date
Feb 2012
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Hello Guys,

i have a question. Is it posbile to start the real time
clock on a Micrologix 1400, from ladder.
When the 1400 (new) arrives, the real time clock is disabled. When the guys load the programm from the memory card to the 1400, the clock doesnt start.
Now i have to go every time to the mashine, connect with my laptop and start the clock.
In the help of Rslogix 500 it says that the bit 7 (clock disabled) of RTC function file is read only.
Is there a way to start the RTC from ladder or from the 1400 LCD?

Best regards,
crawler009
 
Hello Guys,

i have a question. Is it posbile to start the real time
clock on a Micrologix 1400, from ladder.
When the 1400 (new) arrives, the real time clock is disabled. When the guys load the programm from the memory card to the 1400, the clock doesnt start.
Now i have to go every time to the mashine, connect with my laptop and start the clock.
In the help of Rslogix 500 it says that the bit 7 (clock disabled) of RTC function file is read only.
Is there a way to start the RTC from ladder or from the 1400 LCD?

Best regards,
crawler009

Welcome to the Forum!

It does not appear so. I did a bunch of searching on the Knowledgebase, and did not find anything that would help. The MicroLogix PLCs seem to handle the RTC differently than their bigger brothers. I find it odd that it would not start Automatically.

It is still early here, so perhaps someone will come on line with more direct experience with the ML1400.

Stu....
 
I have a new MicroLogix 1400 I can experiment with, but not until next week.

If you load from the memory module, the controller won't have any way to tell what the time and date are.

If you just need the RTC to run, and don't care what actual time and date it shows, I would use several CPW instructions to write values into the RTC on the first scan. See if that works !
 
Hi,
I can't see a way around this one? I have tried before.
On first power up the disable clock bit(RTC:0/DS) is set 1. It is indeed read-only. You cannot write a 0 to it through logic, or even manually in the Function File itself. It's on a toggle with the 2 buttons beside it. You have to press the "Set Date & Time" button to write a 0 to the disable bit and you have to press the "Disable Clock" button to write a 1. We have no way to mimic the actions of these buttons, at least not through logic.

Ken, you cannot write values to the RTC:0 Function File while the disabled bit is set or the controller will fault on Major Error:44h - "Invalid write to RTC Function File".
It has to be enabled first.

The reason it is default disabled out of the box is to save power during long storage before it is sold. It then has this Enable/Disable feature, to start the clock, but disable it again if you were going to store your controller away for awhile. Also if an application doesn't require it, it can remain off.

They must have assumed that all RTC controllers would be "worked on" for the first time in a panel shop, workshop or onsite at commisioning, where the programmer would be present to enable it. We bring 1400's from the stores to the workshop before they go to the floor, so we always have it enabled & program loaded beforehand. We don't use memory modules as yet, but either way I don't see this being possible without a change from Rockwell. If they allowed read/write attributes for RTC:0/DS it would solve this. Perhaps there are other reasons they don't allow it?

G.
 
You have to use CPW instead of MOV instruction and you can do with the time and date whatever you want.
 
Yep, I ran on this post and shared a solution, maybe it will be useful to someone, maybe even in seven years...
 
Let's keep this on track so for those future readers...

mikili said:
You have to use CPW instead of MOV instruction and you can do with the time and date whatever you want...I ran on this post and shared a solution, maybe it will be useful to someone, maybe even in seven years...

Or maybe never?...

Yes, CPW-wise you can "do with the time and date whatever you want" after the RTC has been enabled. But not before that. Out-of-the-box the MicroLogix 1100/1400 RTC may only be manually enabled via the specific user task in the software which I had outlined in my previous post.

Did you read my post? If so, do you disagree with it?

The OP specifically asked...

crawler009 said:
...Is it possible to start the real time clock on a Micrologix 1400, from ladder...

As things stand, the answer to that question is categorically no.

Let's back this up with some hard facts from the manufacturer...

21067 - Using the CPW Instruction to Access RTC Data in MicroLogix Controllers
Access Level: TechConnect

Note that the title refers to "access" and not "enable". Within the text of that technote article, we are specifically instructed to...

Technote 21067 said:
...Make sure the RTC is not disabled. Enable the RTC by clicking on the Set Date & Time button...

Again, what you are outlining is only possible after we have first manually enabled the RTC.

This technote explains what happens if you do attempt to CPW write to the RTC Function File while it is disabled, as I pointed out to Ken previously...

63733 - MicroLogix - Fault 44h - INVALID WRITE TO RTC FUNCTION FILE
Access Level: TechConnect

Technote 63733 said:
...verify the following to prevent this fault: The RTC has been set once by going to the Controller Folder--> Function Files--> RTC Tab --> SET DATE & TIME while online...

...There is a status bit in the function file labeled RTC:0.DS. This bit is for feedback only and does not enable or disable the RTC; the bit cannot be modified in ladder logic or changed manually while offline or online...

And the final hammer blow on this matter...

49250 - How to enable/disable the MicroLogix 1100 or 1400 Real-Time Clock (RTC)
Access Level: TechConnect

Technote 49250 said:
...The MicroLogix 1100 and MicroLogix1400 Real-Time Clock (RTC) can only be enabled or disabled when you are online with the MicroLogix 1100 or MicroLogix 1400. In the RSLogix 500 project, go to the Function Files and click on the RTC tab. To enable the RTC, click on the 'Set Date & Time' button. To disable the RTC, click on the 'Disable Clock' button...

I'm sorry to have "disabled" your solution, but the status quo suggests that no amount of passing time, numerologically seven-yearly or otherwise, will improve upon its "real-time" standings.

Regards,
George
 
Or maybe never?...

Yes, CPW-wise you can "do with the time and date whatever you want" after the RTC has been enabled. But not before that. Out-of-the-box the MicroLogix 1100/1400 RTC may only be manually enabled via the specific user task in the software which I had outlined in my previous post.

Did you read my post? If so, do you disagree with it?

The request is strange in its root.
The question is why "When the guys load the programm from the memory card to the 1400, the clock doesnt start." these guys are loading program from memory card so often "Now i have to go every time to the mashine, connect with my laptop and start the clock." that crawler009 has to download it from RSLogix500 every time...? How many new PLC's those guys are installing? It is not normal that someone is loading program from memory card every time PLC is started. That's why PLC has a battery. Memory card is used as a backup in case battery fails and program gets lost.
AB didn't considered an option that someone would like to enable or disable RTC from ladder and that's fine by me. Use RSLogix500 to enable RTC and check the battery.
 
You cannot invalidate this question..

mikili said:
...The request is strange in its root.
The question is why...

crawler009 said:
...When the guys load the programm from the memory card to the 1400, the clock doesnt start...

mikili said:
...these guys are loading program from memory card so often...

crawler009 said:
...Now i have to go every time to the mashine, connect with my laptop and start the clock...

mikili said:
...that crawler009 has to download it from RSLogix500 every time...? How many new PLC's those guys are installing? It is not normal that someone is loading program from memory card every time PLC is started. That's why PLC has a battery. Memory card is used as a backup in case battery fails and program gets lost...

No. I'm sorry, but that was not the question. That was the reason for the question. The question that was asked is can we enable the MicroLogix 1400 RTC from ladder logic, or indeed the LCD menu, which was also asked. As that question stands, and regardless of why the question may have been originally posed, there is a categorical answer to it, and that is no on both fronts.

That, for me, should be enough to park this quite old thread and not get into those reasons why the question was asked. The reason I say that is not mainly because the thread is years old. It is because the question that was asked has validity in many situations where a user may be provisioning a new MicroLogix controller with RTC and finds that they cannot enable it without the manual use of software.

Attempting to now analyse the reasons why the question was asked in the first place, and in 2012 at that, will not invalidate the question that was asked. It stands itself up.

Regards,
George
 

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