I have device with two ports for modbus:
RS485 and RS232, version of modbus 1.0

I want only reading registers using RS232 (RTU mode), But another program and computer using RS485

How can I know about concurrent access in my situation?
I'm not professional programmer of TCP/IP or Modbus. I couldn't find answer on my question in the internet

 

A device with 2 ports should handle concurrent access just fine. Some devices have 4 or more serial ports & all can work concurrently. If for some reason the device cannot support 2 ports at once, then something in the device should prevent you enabling Modbus on both at the same time.

However, you should avoid supporting 2 masters which plan to write at the same time. For example, many DCS/masters will write a register, then read it back to confirm a successful write. If two masters tried to write the same register (say a control to start or stop a motor), you'd get locked into deadly race (almost an embrace) where the 2 fight over the register, each trying to force it to a different value.

But assuming one port is used with a read-only remote HMI display and the second might be a local display which allows control, then you are fine.

 

> I have device with two ports for modbus:
> RS485 and RS232, version of modbus 1.0

Please post the make and model of your device. Are they actually two ports? Some devices claiming to support both of these standards are actually using the same port for use one at a time.