I connect the PLC S7 1200 to the ignition but It can't read tags, and the designer tag value always showing (BAD), I made multiple changes on the OPC item path for many formats for example [plc_1]IX0,[plc_1]MX1, and [PLC_1]MX1.0.......and others but doesn't work, any advice, please??
The Siemens setup is shown here. Siemens - Ignition User Manual 8.1 - Ignition Documentation.
You haven't mentioned what the status of the device connection is.Check on the gateway | Config | OPC UA | Device Connections.
Then check Config | OPC Client | OPC Quick Client.
Are you using Ignition's native driver or an OPC connection? If the former, have you followed all of the instructions for PLC settings?
If the latter, note that there are some OPC/UA 1.03 vs. 1.04 issues that may need to be resolved. It is a bit of a mess, actually:
https://forum.inductiveautomation.com/search?q=s7-1200%20OPC
(The S7-1500's native OPC is much more Ignition-friendly.)
I am using OPC connection and I follow all the instructions for the tag and gateway connection THe PLC is connected in the Gateway
Then the links that @Transistor and I posted for addressing information doesn't apply. Those are for Ignition's native driver. If you are using the S7-1200's built-in OPC, you must follow its rules for addressing. But also keep in mind that it uses OPC/UA v1.04, where Ignition does v1.03, so there are parts of the S7-1200 implementation that do not work with Ignition. The second link I posted has many discussions of the these caveats.
(I avoid Siemens like the plague, so I have no further advice. Some of the regular Siemens users around here might chime in with more focused advice. It is a holiday weekend in the U.S., so I hope you aren't in a rush.)