Micrologix 1100 Ethernet Message Connections

[k0d3 0]

Good day everyone,

First post here so hopefully I'm not violating community guidelines in anyway.

I've got a system that has some 50 odd Micrologix 1100 and 1400 in use and I'm currently working on setting up an auto timesync for all of them using just 1 of the PLCs that will be my master time PLC. So far I've put together the logic for all the message instructions with the corresponding IP of the slave devices. I'm running. Into an issue with not being able to terminate/break the message connection on a PLC that I have already synced. Is this even possible to do on the ML1100. Once I get to 16-17 messages DN it starts to ER and will not complete any further messages.

What I have is a message instruction ladder with a timed trigger to activate a MSG and write the RTC data then time down and connect and write to the next and so on. When it triggers the message instruction of one PLC it also fires an OTE to trigger the BK of the previous message instruction. However it doesn't seem to be actually cutting the message connection and holds it persistent until a power cycle/download event.

[Joe E. 244]

The manual and knowledgebase say that they support up to 16 outbound connections, so the problem  you're seeing kind of makes sense. I don't know how to release connections that aren't in use any longer. I wonder if you could send 16 messages and then wait a certain time to send the next 16? Connections may expire after a while. For synchronizing time, you shouldn't need to send them all that often. When I synchronized the time across multiple machines, I did it once a day. I also didn't have to synchronize so many. It may pay to have an intermediate device (like a Red Lion HMI or datastation or something) handle the comms since there are so many devices with relatively limited Ethernet capabilities.

ETA:

Or, here's another thought. You could have your first master send the updated time to 10 others and then have each of those 10 send the update to a handful each. If you have 50 total, PLC1 would send to 10 others and each of them would send to 3 or 4. There would be a short but very minimal lag between them, but if you're time stamping data or want to display the time on each, that shouldn't even be noticeable. Of course, if you're doing something much more critical than that, you're probably  not using Micrologix anyway...

Edited 8 Nov 2021 by Joe E.

[k0d3 0]

Thanks for the reply Joe. I actually utilize some Graphite G07s and can easily pass it through the HMI gateway. I am definitely not solid with Redlions and I'm not sure how to go about pulling the direct RTC:0 word into the HMI for the distribution using the standard Allen Bradley driver. I suppose I could use a CPW function and populate a holding register of sorts then using that push it out and use another CPW in each connected PLC to push it back into their RTC file. Would you happen to know if the RTC is viewed as a Long Integer or what data format would work best?

[Joe E. 244]

When I set up time synchronizing between PLCs, it was always part of a larger data sharing system so I had an array of integers already going back and forth. I just packed the date and time into a few of the integer registers to send around. I'd probably do something similar here.

If you want to use the Graphite HMI, look into gateway blocks. The first time you set them up it's a little...weird....but they do work really well. I had a G304 Kadet (their smallest and cheapest HMI at the time) talking directly to a PLC5 via serial port and serving as a data gateway to get information between that PLC5, 3 Siemens S7-300s, and a ControlLogix. It was also displaying data directly from the ControlLogix. I would probably set up the gateway blocks to transfer some number of integer registers (more than you need right now) and then pack/unpack the date/time info at either end.

[k0d3 0]

I greatly appreciate the help. I'm going to work on it and I'll update the post with the final solution. But I rather do like using my HMIs to handle the network side of things. Thank you again.

[BobLfoot 281]

You might also want to consider the free Rockwell CLock Update Tool - https://rockwellautomation.custhelp.com/ci/fattach/get/120196/ 

Assuming you have a SCADA PC or Master Programming PC to place it on.

[k0d3 0]

I was under the impression that the Rockwell clock update was only applicable to controllogix PLCs. I'll look into it for micrologix. Thank you.

[Ken Moore 23]

I have used the Rockwell clock tool with PLC5/25's through a ethernetIP/DataHwy Bridge, so Micrologix should be a piece of cake.

I used a one hour update and the PLC-5's via the gateway were off about 200 milliseconds, close enough for my task.

 

BTW, I find the tool works best on a server class machine, it does not run as a service, so you can't log off and have it work, on a standard PC. 

[Ken Roach 190]

For MicroLogix and other legacy controller, you want the "Logix 5000 Clock Update Tool".   It is stable but development has been discontinued as of version 3.0.0, which I think came out this year.

https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/44321

For bigger or more sophisticated ControlLogix systems, there's a IEEE 1588 based tool called the Studio 5000 Clock Sync Tool.

I'm sure there's a good technical reason that RA never just implemented Network Time Protocol, but they didn't.

[pturmel 117]

IEEE 1588 Precision Time Protocol is the native clock protocol for Logix 5000 time synchronization.  Just turn it on where needed.  No tool required, just a precision source.  I've had success with Time Machines TM2000B GPS clocks--just set it to multicast PTP.  (~ $500.)

[pturmel 117]

(PTP is dramatically more precise than NTP--that's your technical reason.)