[Dx4win] Communication between DX4WIN and IC7600 does not work

[Mel SM0MPV]

Communication between DX4WIN and my ICOM 7600 does not work.

If I would like to grab a station from the Band Map the frequency changes
accordingly in the Frequency field but after approximately 5 seconds it
changes back to the previous frequency and nothing happens on the radio.

However, information from radio to program works nicely. If I turn the VFO
frequency changes in the Frequency field accordingly. The same is true for
band and mode changes.

Both N1MM and DXlog works nicely both directions.
I need help with suggestions what to do?
-- 
73 de Mel - SM0MPV
8S0C - Contest Call

Radio: ICOM 7600
Computor: IBM Thinkpad, X230, Processor i7-3250 CPU 2.90 GHz
Docking station: ThinkPad UltraBase Serie
Connection: USB-cable

Silicon Labs CP210X USB to UART Bridge v. 10.1.8.2466
     ‒ Port settings 9600 Bit/s, 8, N, 1, Flow control: None

Windows 10 v.1903

DX4WIN v. 9.0.6.1228
Rig settings:
     ‒ ICOM 7600_250MHz by ON4AOI
     ‒ Address 7A
     ‒ Baud rate 9600
     ‒ Poll rate 5000 ms
     ‒ Max tries 6
     ‒ DTR high and RTS high both enabled