modbus poll communication problem

Hello, esteemed seniors

When we communicate via Modbus RS485 using the Modbus Poll program, we have two slaves. We can receive/send signals normally.

However, once we open the communication window, one of the slave encounters a timeout error.

What step might we have done wrong?

Thank you!
What do you have your Response Timeout setting set to in Modbus Poll's Connection Setup window? Do you still see timeout errors if you increase the Response Timeout?

Just to confirm, are your two slaves set to different addresses?