How to Reset RTC Clock on Compact-Logix?

[alive15]

Good afternoon all, hope everyone is doing well. I have a Compact Logix PLC that has an RTC module installed on it. About every year, it loses the correct time and date, and I have to manually connect with a laptop to "set the time/date to match workstation". Is there any bit I can use to reset this on an HMI perhaps, or is the only way to set the time through the workstation?

See picture attached, in the current location where the time and date is, it was originally showing "???".

Thanks,

 

[Ken Roach]

What sort of RTC module is installed on/in the controller ?

In general, the clock on a CompactLogix is held up by the 3V lithium battery (first 2 generations) or a supercapacitor. I'm not familiar with a clock module, like existed for the MicroLogix 1200 and 1500.

What's happening to you sounds more like an unplanned power outage.

 

[alive15]

Yes, we did have a power outage last week, so that is probably why it messed up. However, I'm trying to find a way for our technicians to reset the time automatically through an HMI using some bit in the PLC if possible. I transfer the PLC's date and time to a dot-peen marker which etches current date/time onto a part upon cycle complete, so if it happens during the night, they wait until an engineer comes in during the morning to reset it manually through the laptop. I don't think there is, as there is no system to tell the PLC what time/date, but just checking my options.

 

[drbitboy]

I think @dmroeder had some recent success working with the RTC from pylogix, but I might be conflating multiple threads from multiple sources.

 

[Ken Roach]

[Rubs hands together gleefully]

What sort of HMI is it ? PanelView Plus has a clumsy "Global Connections" mechanism for connecting the PV+ operating system time to the PLC.

What exact model of CompactLogix is it ?

Does your automation network have access to an NTP server, or outbound access to the Internet ?

This could be as complex as a Logix AOI to implement NTP Client, or as simple as "operator punches in Date/Time to a screen and presses an APPLY button" that makes the CompactLogix apply the date/time using the Set System Variable (SSV) instruction.

 

[Operaghost]

You can write logic in the PLC to set the clock. Have the HMI write the time to the tags. If your HMI is a PanelView Plus they have what is called a Global Connection setting that can be used to sync the clocks regularly. EDIT: Yes, it can be a bit clumsy to set up).

OG

 

[dmroeder]

I think @dmroeder had some recent success working with the RTC from pylogix, but I might be conflating multiple threads from multiple sources.

I had been able to set the clock for a long time, I recently added setting DST

 

[Ken Roach]

The reason I call the PV+ mechanism "clumsy" are multiple:

1. It relies on the Windows CE system time in the PanelView Plus. Most PV+ terminals are not set up to be members of a Windows domain, and therefore they don't get a time automatically like your average PC connected in an office does.

The PV+ also doesn't have an ordinary Network Time Protocol (NTP) Client that you could point toward a computer serving as a time server on your network, or even point toward an Internet based time server like time.windows.com or NIST.gov.

I'm ready to be wrong, but I don't know of one, even on the PV+7.

2. It relies on the user to write their own logic to apply seven arbitrary tags to the controller's Wall Clock Time object. I don't think I've ever seen a simple but thorough application example.

Oh and another thing:

3. The Global Connections tab is confusing. I have been using that software for nearly 20 years and every damn time I look at it I have to remind myself which set of tags are the ones being read by the PV+, and which ones are being written to the PLC. The Help file refers to both reading and writing as "updating" and to the PLC and the PV+ as "local" and "remote". You can screw it up, including creating a circular update condition by using the same tags, and Logix 5000 won't even try to warn you.

 

[Ken Roach]

I swear, every system I build from now on with ControlLogix is going to have a Revolution Pi Core snapped in next to the Ethernet switch just so I can do middleware stuff like this when I want.

If you've got a simple PLC system that needs to keep up with the world's timekeeping services to within a second or so, it's straightforward to just use the very old, very simple TIME service. You make a TCP connection to Port 37 of one of those servers, and it replies with a 4-byte value that is the number of seconds since January 1, 1900.

 

[Ken Roach]

Before I go too far off into the weeds, there has been a Logix AOI for NTP for several years. If you have a CompactLogix that supports open sockets (anything newer than the 1769-L32E/L35E generation), that's the best way to get a decent time reference into your controller over the network.

https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/493378