View Full Version : Okuma Cadet-Mate RS232/Serial port use?

06-20-2007, 05:02 PM

We have some more complex than usual shapes we need to mill and it seems like we really need to know how to use the serial port and mastercam/CIMCO to connect a laptop computer to the machine and run a milling sequence.

Is there a special interface required, or will a standard RS232 serial DB9 to DB25 work? Does it need to be a straight through (null modem) or a regular rs232 cable? Thanks in advance.

06-21-2007, 08:35 AM
070621-0656 EST USA


I do not have specific knowledge on Okuma.

I personally do not like the terms "null" modem and "standard" as applied to an RS232 cable. There are too many variations.

Here is my suggestion to solve your problem.

First, decide if you will use software or hardware handshake. Software handshake would include XMODEM if Okuma has that capability.

Software handshake only requires 3 wires, unless Okuma has some special requirements in this mode. Hardware handshake will require at least 5 wires.

If you always describe an RS232 port by the function of a pin, TxD for transimit, RxD for receive, and Common for signal common and assuming software handshake, then Common gets connected to the other Common, and TxD of one end is connected to RxD of the other end.

The 25 pin connector at the Okuma probably has pin 2 as TxD, pin 3 as RxD, and pin 7 as Common. You can identify TxD at rest, no data being transferred, by a -5 to -15 V level relative to Common. On some laptops this won't work as an identifier because to conserve power the RS232 driver is disabled at rest. The RxD will be near 0 V relative to Common. Obviously this is without anything connected to the pins except the voltmeter.

The 9 pin connector at the PC should have pin 2 as RxD, pin 3 as TxD, and pin 5 as Common.

So likely your cable will be pin 2 to 2, pin 3 to 3, and pin 7 to 5. At Okuma you will probably have to connect pin 4 to 5, and separately 6, 8, and 20 together.

You may find some useful information at my web site
www.beta-a2.com .

Is this enough for you to get started?