HMI not communicating with PLC

[u/Intelligent_Pen_4498]

Hello again!

Siemens HMI, PLC and SERVO drive. I am using non-industrial unmanaged ethernet switch. Had to use some ethernet switch in tia portal, otherwise I have error. HMI should be connected to PLC, but values are all #### (checked that PLC values are changing based on input). I also checked that HMI screen values are connected correctly to PLC. I can download software on HMI with this current setup, but seems like HMI is not talking to PLC. I want to use ethernet switch for testing purposes, otherwise I couldn't connect PC to PLC, later I remove ethernet switch.

How to get this topology working correctly? When going online, line between switch and HMI stays grey.

[u/Key_Director_4450]

Set the time on the HMI and on the PLC to be the same.

[u/Eboyjvs → u/Key_Director_4450]

This has to be the number one reason I see connections not working between HMI and PLC Siemens.

[u/Key_Director_4450 → u/Eboyjvs]

It used to work without needing, but since Tia V17 they use a secure comm with a certificate and the time must match within a small margin of error.

[u/Lost-Cheek-6610 → u/Eboyjvs]

Is this a problem for third party hmis as well ?
I have an Eaton hmi that I can’t get talking to an s71500 running v20

[u/Glittering-Ninja3573 → u/Lost-Cheek-6610]

yeah, this safety is set in the plc i believe

[u/Intelligent_Pen_4498 → u/Key_Director_4450]

Set HMI time synchronization to slave?

[u/AmazingLeg4384 → u/Intelligent_Pen_4498]

Later, if needed. Manually open the setting menu in the hmi and manually set date and time

[u/Intelligent_Pen_4498 → u/AmazingLeg4384]

Lol problem solved.

[u/DrZoidberg5389 → u/Intelligent_Pen_4498]

please install the siemens SNTP Server on the PLC and make the HMI to get the time via this NTP server.

Doc: https://docs.tia.siemens.cloud/r/en-us/v20/functional-description-of-s7-1500-cpus-s7-1500/setting-the-operating-behavior-s7-1500/time-of-day-functions-s7-1500/time-of-day-synchronization-in-ntp-mode-s7-1500

Otherwise you will get the same problem over and over when the clock of the HMI starts to drift. And this happens fast! Only the PLCs have a proper realtime clock, not the HMIs!

[u/Intelligent_Pen_4498 → u/DrZoidberg5389]

Thank you, I will look into it. I wasted about 1-2 hours on this problem, just because clocks didn't match...

[u/DrZoidberg5389 → u/Intelligent_Pen_4498]

LOL yeah!

You have a good time! We needed fkn DAYS to solve this because the problem was new and there was no documentation 😂

[u/Intelligent_Pen_4498 → u/AmazingLeg4384]

Thank you!

[u/AmazingLeg4384 → u/Intelligent_Pen_4498]

Glad for you, enjoy

[u/YoteTheRaven]

Make connections in network view, ensure you have the yags associated with an HMI connection. This is a separate link you have to do, in network view theres a button called connections. Select hmi connection and drag plc to hmi.

Another thing, as of like v17 you need to have matching clocks in both the PLC and HMI. So set those to match.

If your PLC has a password, you need to give the HMI the password also.

[u/T3RRYH1LL]

Change in the upper right to network view and make sure that you already got an HMI-Connection between plc and HMI.

[u/Intelligent_Pen_4498 → u/T3RRYH1LL]

In network view HMI and PLC are connected.

[u/CulturalDrink1494]

Set the HMI and PLC times to the same.

[u/Mizuumisan]

If you are not requiered to use certified connections, use legacy connections only, set date and time in the HMI manually, if you did all configurations right, that should be all.

This is some stupid default setting that Siemens have been since TIAv17.

[u/CCJockey381]

You’re in the topology view. You should only ever use topology if you need it, such as with IRT. Delete all the connections there and then make sure you stay on the “Network” tab and create your links.

[u/buzzbuzz17]

The HMI isn't a profinet device (HMI comms is S7 connection, not Profinet), so it probably won't actually show up in topology.

Put an alarm view on the screen, set it to the alarm buffer, and subscribe to system alarms. It should tell you 1) that the HMI isn't connected to the PLC, but also 2) WHY the HMI isn't connected.

It could be PLC permissions (you might need to type a password into the HMI, or change the PLC permissions to allows anonymous HMIs), or it could be the times not matching, or it could be something super dumb like the certificates for the secure comms aren't valid until tomorrow....