Experimental Physics and
Industrial Control System

I think the Official TCP port for telnet is 23.  “telnet 192.168.0.21 1” may not work anyway (TCP Port 1 is TCPMUX).

 

For Ethernet/RS232 converter, the port number usually is the TCP port number (usually > 1024), not the physical RS-232 port number (1, 2, 3, 4). In your case, you might use drvAsynIPPortConfigure("L0 ","192.168.0.21:***1") instead of drvAsynIPPortConfigure("L0 ","192.168.0.21:1") for the RS-232 port 1.

Anyway, you need to read the NI converter manual and find out if it has web server running. Then, type 192.168.0.21 in your web Browser and try to find out the information about the TCP port and RS-232 configuration.   

 

Good luck,

 

Yong