Communication Protocol Suggestion

[mahmoud shahien]

Dear Experts ,

I have a system which contains 10 PLCs (1214C CPU) each PLC with GSM module (Teltonika RUT955) and 2 SCADA PCs at different locations (attached the Architecture) and I need to establish communication remotely between the 2 main SCADA and the 10 PLCs over GSM, I will use static IP SIM cards at each PLC.
The client has the below requirements:
- Siemens PLC should be communicated with SCADA system on specific Schedule Time.
- In normal condition (if no any Alarm), each site will communicate with SCADA system four times a day.
-There should be assign an option in SCADA system to poll the data of any site whenever he require.
-If any Instrument value will change to its Alarming stage or any other critical Alarm take place, Then that site should communicate with SCADA system and transfer the information immediately.
- Low data consumption.


So, according to the A/M system, which the best protocol you suggest that we can use?
Can Profinet communication comply with the requirements, or what is the best cost effective solution to comply with the client requirements?
Thanks.

 

[Saffa]

What is the SCADA system?

I am no expert with Profinet, but I believe it is intended for a master-slave (excuse non-woke terminology) arrangement where the SCADA server polls each PLC. I don't know of any SCADA systems that support acting as a profinet slave, to allow the remote to initiate communications.

You'd need a data concentrator PLC at each SCADA server and set up each slave to write to that data concentrator. But then you'd also need to able to command the data concentrator to poll the slave if commanded by the SCADA.

Typical protocols don't work well with this "I'll ask you for data, but sometimes you send me data without me asking" approach.

I use the DNP3 protocol a lot, and this is the perfect application for it. However, it does mean an add-on for each Siemens PLC and a Scada server that supports it.

 

[lfe]

The first thing necessary with the current protocols used is to establish a TCP/IP connection and that cannot be achieved with only GSM which is currently only used to transmit voice calls or SMS messages.

The remote station should connect via 3G/4G/5G through which TCP/IP connection can be established.

Normally this connection could be always active and connected, in the same way as mobile phones that are always connected
If you want to limit the data traffic, the SCADA system will simply have to interrogate the remote stations in long periods of time, although surely the amount of data transmitted will be much smaller than what is thought

Ideally for me, the remote stations should have a 3G/4G/5G router with the ability to connect VPN with the following advantages:
- It is not necessary that the stations have a static & public IP, any data SIM card will work
- Secure connection with encrypted data
- The connection can also be used to remotely program the PLC.