Make sure you are using a null modem cable. Troubleshoot the connection by using a com port on your PC to connect to the rcvr. Use a comm program on the PC to send the command strings.

Also, make sure that you remove the extra "\" character from the RS232 command strings in the URC database. Most of the devices in the database which have ASCII command strings containing unprintable characters have the extra "\" character.

For example, power on command for Yammy RX-V1900 is listed in the database as "\\x0207E7E\\x03, it should be "\x0207E7E\x03".