Your RS485 port is being used by XServer and when you perform online monitoring via XServer, the COMM3 port (RS485) is working in slave mode. But when you try to run NETCMD$ to talk to an E10 as slave, you are trying to use the COMM3 as master and as soon as the PLC start sending data out of the COMM3 port it interferes with the online monitoring. This will not work.
Also if the E10 and the PLC are not set to the same Baud rate, then the PLC attempts to communicate with the E10 will fail, which cause the PLC to slow down since it is repeatedly trying to make connection with the E10. You need to either change the T100MD COMM3 port or the E10 serial port to the same baud rate.
What you need to do is to turn DIP switch #4 ON to stop the PLC from running the program, then transfer a program without the running NETCMD$ (perhaps your original program) into the PLC. Then turn off DIP switch #4.
Unfortunately you have reached the limit of what T100MD+ PLC can do. If you want to be able to connect to the PLC via the Internet, allows it to send email and also interface to HMI, GSM modem, and E10 as slave, you should consider using a F2424 which has built-in Ethernet port (so it doesn't need XServer), and you still have 1 RS232 port and 2 RS485 ports available. In fact a T100MD1616+XServer would cost more than the F2424 so that results in some cost saving if you are building new equipment.
