Hi,
Thank you for the fast answer. The RUT955 should send the character string to the server (for identification), not to the connected device on the RS232 port.
Maybe the "modem" mode is also the wrong one. We have a device with rs232 connection on the RUT955. RUT955 should connect to a server via IP with a character string. All traffic between the server should then go to the device via the RS232 port.