LAN connection via ST-Lite to Q03 CPU PLC

[JanHrust]

Hi I need a little help please with networking through ST Lite. The scenario. I have a Q03UDECPU (Ethernet CPU) PLC which need to connect to STL-ETH1 (ST-Lite unit) unit and then also to the LAN for the MAPS SCADA to be able to read it. Now the STL-ETH unit has 2 network ports that I can use. However, I need to know if a daisy chain type of configuration will work. Basically LAN --> Port 1 on ST-lite and from Port 2 -- PLC and then back the same route. Is this possible? Reason for this is because I only have 1 network connection available from the LAN.

[Gambit]

Two ETHERNET interfaces and an integrated switch allow the fieldbus to be wired in a line topology. This eliminates additional network devices such as switches or hubs. Both interfaces support Auto-Negotiation and Auto-MDI(X). Looks like you can daisy chain.

[JanHrust]

Okay thanks. The next question is how would I map the I/O from the ST unit in my PLC then? Do I need to setup some sort of Protocol (MC, Melsoft or Socket protocol)?

[Gambit]

You'll need to set up mobus TCP So you need a QJ71MT91 module or use the predefined protocol support function.

[JanHrust]

Okay, do I need to plug the network cable from the STL-ETH1 into the QJ71MT91 module? Will I still be able to communicate via ethernet protocol also to the PLC?

[Gambit]

The QJ71MT91 also support one (or more configure in parameters) connections to the PLC for SCADA or programming.

[JanHrust]

Thanks, that is great news! Will post my progress for future assistance.

[JanHrust]

Just an update. Got all working. ST-Lite to QJ71MT91 (Modbus dedicated) and then my access to the Ethernet network was through my Q3UDECPU onboard Ethernet port. Had some issues assigning the correct length of my address, but once that was sorted, it was smooth sailing. Just a note. It does not matter how you cards installed on your unit (digitals and analogs, input and outputs), your analog cards will always take the first addressing. Took me a while to figure this out.