TTL232 is an embedded converter of RS232 serial line signals to TTL signals. Its miniature footprint makes it simple to embed into an RS232 connector cover (D-Sub9, Cannon9).
Simplified converter diagram
Please do not hesistate to contact us in case you need any custome midification done to the TTL232 device.
If you are using third-party software: Look for Enable DTR, Enable RTS, or similar settings. It is also possible that the software sets the DTR and RTS signals automatically. This can be verified by measuring a voltage greater than approx. 7 V on pins number 4 or 7 on RS232 with a multimeter (measured against terminal no. 5, which is ground).
If you are writting your own software: Set the DTR or RTS signals to the active level (L). For example, in the .NET (C #, VB) programming environment, these are the SerialPort.DtrEnable and SerialPort.RtsEnable properties, respectively.