Hi,
I have a similar problem with the PC-PLC connection. PC Win10 VisiLogic 9.8.91and PLC SAMBA SM35-J-R20.
I connected many times modifying the plc program without problems. When I changed and uploaded the MODBUS connection data, an error 206 (communication driver error) appeared. Now I can't connect and change anything. The PLC only has a RS232 RJ11 port. I am using Unitronics RS232-CB1 cable.
What should I do?