Do you mean the receive command is not correct， instead of no command?
First of all, check if the hardware has been connected correctly.
Secondly, check if you choose the correct serial port.
thank you for your quick response.
The port is correct, i assume that from the timings when the unreadable output appear in putty.
The cable is the original which came with the kit. Also reboots are not helpful.
Thank you very much,
If HW connection and setting are correct, the next is check the firmware running in the 4200 chip is free of problem, some other discussion about using Putty in this community: