sanmotion rs2a03a0al0w00

Good morning, I recovered two years ago some of these drives: sanmotion r rs2a03a0al0w00. I tried to communicate with its R-Setup software and they connected to the PC without any problems even if they gave an encoder error because it was not connected (I don't have motors). A few days ago I tried to reconnect the PC but they don't want to communicate... and yet I set the group parameter to 20 on 01 which is the unit number and 21 to 05 which corresponds to 38,400 I used a PC with native serial, Windows 7, set the serial buffers to a minimum as explained in an article on connecting these drives. If anyone can help me, I thank you in advance. Greetings Mauro