[tmccar]

I want to make up a 9-pin to 9-pin cable for downloading to an Ajax CNC lathe. What pin-to-pin connections should I have?

2--3
3--2
5--5

??

[tmccar]

..Control is a Fagor 800T

[Parikhn]

Standard Null Modem (Crossed) RS-232 Pinout:
Pin 2 -> Pin 3 (TX → RX)
Pin 3 -> Pin 2 (RX → TX)
Pin 5 -> Pin 5 (Ground)
Pin 7 -> Pin 8 (RTS → CTS)
Pin 8 -> Pin 7 (CTS → RTS)
Pin 6 -> Pin 4 (DSR → DTR)
Pin 4 -> Pin 6 (DTR → DSR)
Pin 1 -> Pin 1 (Carrier Detect → Carrier Detect, optional)
Pin 9 -> Pin 9 (Ring Indicator → Ring Indicator, optional)

Simplified (Common) Wiring:

If your CNC lathe does not use hardware handshaking, then you’re right- the minimum required connections are:
Pin 2 -> Pin 3
Pin 3 -> Pin 2
Pin 5 -> Pin 5

[tmccar]

Thanks - I will try it