Syncing Multiple PLC Times

sparkie · Apr 16, 2016

We have several PLC's that are on our controls network (which is actually a pretty strong network). We have several issues that can be solved by syncing the time on our networked PLCs to our networks.

I noticed there is a logix time update utility, which would work for our CLX and above systems, but what about for our older SLC/MLX systems? Has anyone had experience with something like this as I havn't found much information on it.

AustralIan · Apr 17, 2016

1. In your SCADA have an event that writes SCADA TIME to each PLC. In code, write this value to the appropriate S:xx address;
OR
2. set up a MSG instruction to READ the wallclock time from a CLX then write this to the appropriate S:xx address

sparkie · Apr 17, 2016

Okay, sounds good. Basically we have many, many systems (around 30) and 5 different scada systems. I want to sync them all to the same time. I'm setting up a rockwell VM on our servers to handle such things, but was curious if I would have to add the logic manually to each.

OkiePC · Apr 17, 2016

It has been my experience that the Clock Update Tool will work with SLC and Micrologix controllers. I have not used in in many years and I seem to recall that there are exceptions, but we used it with SLC 5/04 PLCs on the network via NET-ENI modules, Digi IAP modules and SLC 5/05 as well as Logix 5k controllers.

Pete.S. · Apr 17, 2016

Can't you sync the PLCs directly to a time server (NTP server)?

I've done it like that a couple of time. One (or two) NTP servers and every computer that needs accurate time is synced directly to the NTP server (those computers with less accurate time needs are synced to the domain controller). Then all PLCs and other network devices like routers, firewalls, industrial printers etc are synced to the NTP servers.

Almost all devices today have NTP capability.

sparkie · Apr 17, 2016

Actually, I can sync them directly to NTP servers, but I have not found any information on how to do that. I would actually prefer them to be synced to our NTP to match the rest of the computers in our facility.

Ken Roach · Apr 17, 2016

Almost all devices today have NTP capability.

You would think that an industry-leading controller would have this feature, but none of Rockwell Automation's controllers do.

I can understand the risks involved in changing the controller time automatically, but since it can be done manually from the editing software, the clock must be technically capable of it.

The Logix 5000 Clock Update Tool is the way to go.

Ben Pugh · Apr 17, 2016

Rockwell has some sample code that will sync the time in a Logix based PLC with an NTP server assuming that the PLC in question supports sockets. It has worked particularly well for me combined with Rockwell's sample code for Daylight Savings Time.
https://rockwellautomation.custhelp.com/app/answers/detail/a_id/493378
(Access Level: Everyone)
If you don't know which PLCs support sockets, basically it is newer CompactLogix hardware and ControlLogix network cards other than an ENBT.

sparkie · Apr 17, 2016

Thanks on this one guys. Looks like the clock update tool can do this if I keep it running on a computer. Fortunately I have access to our servers, so it should not be an issue to keep it running 24/7/365

Syncing Multiple PLC Times

sparkie

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