Hi, could you please help me to understand how to read Siemens S7 1200 registers starting from the following input?
To interact with the PLC I have an OP operate panel (Xinje OP320) connected via RS 485.
I need to read the same data just quering the PLC but via standard modbus TCP IP, and for this I'm using node-red-contrib-modbus.
I've tryed several ways but nothing. The OP works correctly, and here you can see a testing page:
Hi,
in order to receive some help, please share some details about your hardware configuration.
If I understand correctly, you are trying to read the PLC modbus registers via Modbus TCP/IP from your PC with Node-RED. Is that right?
Can you ping the PLC from your PC? In the PLC how is the modbus server configured? Since the RS-485 communication is working, I guess you configured a Modbus slave FB in the PLC program; for Modbus TCP you probably need a specific (different) FB.
Thanks @MountainKing91. Yes I can ping the PLC. Actually I thougth I could reach the PLC via modbus TCP but this is not correct. Yes, I can reach it via TCP but using S7 protocol, not modbus. Infact I can read and write data directly in node-red just using node-red contrib s7.
The problem is that the only information I have are the registers set in the OP operate panel, as for the above image. So I 'm trying to understand if there is a way to read/write those exact registers in order to remote the panel
In your plc program you should have the "MB_SLAVE" function block which sets up the modbus slave and all the registers. Somewhere in the plc program you should have a bunch of networks where you map specific variables to the modbus slave registers.
It all comes down to how you set up the slave, can you take a look at the plc program?
